Bouncycastle Bc Java

Bouncy Castle Java <1.86: External Commit Remove Exploit in MLS
CVE-2026-71890 8.7 - High - October 03, 2026

In Bouncy Castle for Java before 1.86, validation of an MLS (RFC 9420) external commit's proposal list, org.bouncycastle.mls.protocol.Group.validateExternalCachedProposals, counted the proposals by type and bounded the removed leaf index but never established that the removed leaf had anything to do with the joiner. RFC 9420 sec. 12.2 permits at most one Remove proposal in an external commit, with which the joiner removes an old version of themselves, and requires that where one is present the LeafNode in the commit's path field meet the criteria it would have to meet in an Update for the removed leaf, in particular that its credential present identifiers acceptable for the removed participant. The ordinary proposal-list validator's self-remove rule is deliberately not applied on this path, because a resync commit legitimately removes a leaf the joiner owns, but nothing was put in its place. Any party holding the group's public GroupInfo, which is precisely what an external joiner is meant to be given, could therefore commit a Remove naming any member's LeafIndex and have every member apply it, evicting that member and taking over their slot in the ratchet tree. The credential check that should have prevented this existed only in the gRPC interop harness and so protected no other caller of the public Group.externalJoin and Group.handle API. An external commit carrying a Remove is now accepted only when the removed leaf's credential is identical to the one in the joiner's own new leaf, on both the sending and the receiving side.

AuthZ

Bouncy Castle <1.86: BLS12-381 keyValidate flaw permits phantom signer
CVE-2026-71891 7.1 - High - October 03, 2026

In Bouncy Castle for Java before 1.86, BLS12_381BasicScheme.keyValidate, and so BLSPublicKeyParameters and every BasicScheme, MessageAugmentation and ProofOfPossession verify and aggregateVerify that gate on it, accepted a public key built on a foreign ECCurve that merely shares BLS12-381's field characteristic. The prime-order subgroup check trusts a point's own curve to name its cofactor, since ECPoint.satisfiesOrder returns true outright when the curve's cofactor is one, so a point on a curve with a different equation and a cofactor forged to one passed keyValidate despite not being a G1 point at all. In BC's pairing implementation such a point contributes the identity in the target group, so an aggregate signature verified against a set of public keys including it is accepted even though it contains no signature for that key and message pair, admitting a phantom signer. keyValidate now first confirms that the point's curve carries exactly the canonical G1 field, equation, order and cofactor before any subgroup check. The issue is reachable only where an application constructs an ECPoint on an explicit, non-canonical curve and accepts it as an authority-bearing key; the standard 48-byte compressed-point decoder always supplies the canonical curve and was never affected.

Improper Verification of Cryptographic Signature

Bouncy Castle Java: HQC Private Key Leak via Cache Timing (pre 1.86)
CVE-2026-18040 5.9 - Medium - October 03, 2026

In Bouncy Castle for Java before 1.86, HQC leaked secret-derived data through two side channels: its GF(2^8) arithmetic used lookup tables indexed by field elements, making the cache line touched a function of the operand, and its fixed-weight support sampler left its duplicate scan as soon as a collision was found and stored accepted positions at a secret index. Both run on secret inputs during encapsulation and decapsulation, and the sampler re-expands the secret key from its seed on every decapsulation, so an attacker able to observe cache behaviour or decapsulation timing can recover information about the HQC private key. The field arithmetic is now table-free and the sampler branch-free within a batch of candidates, with output and randomness consumption unchanged.

Observable Timing Discrepancy

Bouncy Castle Java MLS <1.86: Unsigned X509 Cred Bind (CVE-2026-71885)
CVE-2026-71885 9.2 - Critical - October 03, 2026

In Bouncy Castle for Java before 1.86, the Messaging Layer Security (MLS, RFC 9420) implementation did not bind an X.509 credential to a LeafNode's signature_key. LeafNode.verify() checked a leaf's signature against the signature_key carried in the leaf itself, while the credential's X.509 certificate chain was stored but never parsed or validated, so the end-entity certificate's public key was never required to match signature_key as RFC 9420 sec. 5.3 requires. A party could therefore present another party's certificate as its credential while signing the leaf, and the enclosing KeyPackage, with an unrelated key, and be accepted under that other party's identity through KeyPackage.verify() and the Group leaf-validation path. In a deployment that admits external commits without an independent credential-admission check, an unauthenticated attacker could be admitted under a victim's X.509 identity, evict the victim (resynchronization compares whole credentials rather than signing keys), derive the current epoch, decrypt subsequent group messages, and send messages accepted as the victim. TreeKEM.LeafNode now requires the end-entity certificate's subject public key, in the cipher suite's signature encoding, to equal signature_key for an X.509 credential and rejects the leaf otherwise, including an empty chain or a certificate whose key type does not match the cipher suite; certificate-chain and identity validation to a trust anchor remain the application's responsibility per RFC 9420 sec. 5.3.1. Deployments using only basic credentials are unaffected.

Improper Certificate Validation

Bouncy Castle Java Pre-1.86 API Bypass via Non-CERTIFY_SUB Key
CVE-2026-71886 8.2 - High - October 03, 2026

In Bouncy Castle for Java before 1.86, the high-level OpenPGP certificate API accepted a third-party certification or trust delegation from any component key of the issuing certificate, without requiring that component to have been granted the authority to certify. OpenPGPCertificate.getCertificationBy() and getDelegationBy() resolve a third-party signature by matching its issuer key identifier against every key of the third-party certificate, then verify the issuing component's binding chain and the signature itself; nothing checked that the issuing component carried the RFC 9580 sec. 5.2.3.29 certification key flag (CERTIFY_OTHER) when the signature was created. A subkey bound only with SIGN_DATA - the online signing subkey of exactly the offline-primary arrangement those key flags exist to express - could therefore issue a positive User ID certification over an attacker-controlled identity, or a full-trust depth-one direct-key delegation of introducer trust, and the API returned it as a valid signature chain attributed to the third-party certificate. An application treating getCertificationBy(...).isValid() or getDelegationBy(...) as an identity or trusted-introducer decision would attribute the attacker's assertion to the offline primary key. The same held for a legacy RSA subkey bound only for encryption, whose algorithm is nonetheless able to sign. This does not forge the primary key's signature or recover any private key; it promotes an already-compromised restricted subkey to the primary key's identity-issuing authority, defeating the containment the key-flag separation provides. A third-party certification or delegation is now attributed to the issuing certificate only when the component key that made it is the primary key, or is a subkey holding CERTIFY_OTHER when the signature was created, so certification-capable subkeys continue to be accepted; primary keys are accepted whatever their key flags say, since a primary key is certification-capable by construction and certificates carrying no key flags subpacket at all are common. Third-party revocations are deliberately outside the rule, since declining to honour one would keep trust alive rather than withdraw it.

AuthZ

Bouncy Castle Java OpenPGP API <1.86 CrossCertification Vulnerability
CVE-2026-71887 8.2 - High - October 03, 2026

In Bouncy Castle for Java before 1.86, the high-level OpenPGP API accepted a data signature made by a signing subkey whose Subkey Binding signature carried no embedded Primary Key Binding (cross-certification) signature, in the case where that binding omits a Key Flags subpacket. RFC 9580 sec. 5.2.1.8 and sec. 10.1.3 require the embedded Primary Key Binding signature on any subkey that can issue signatures; it is the subkey's own statement that it belongs to the primary key it is bound under. OpenPGPCertificate resolved the subkey's key flags two different ways. isSigningKey() goes through getKeyFlags() and getApplyingSubpacket(), which falls back to the primary key's direct-key or primary User ID self-signature when the binding signature omits the subpacket, so the subkey inherited the primary's SIGN_DATA and counted as signing-capable; verifyEmbeddedPrimaryKeyBinding(), which enforces the requirement, reads the binding signature's own hashed subpackets, found no SIGN_DATA there, and returned early as a non-signing key without ever demanding the back signature. The same subkey was therefore signing-capable - so its signatures were attributed to the certificate and OpenPGPSignature.OpenPGPDocumentSignature.isValid() returned true - while being exempt from cross-certification, where GnuPG refuses the identical certificate and message. An attacker needs only the victim's public signing subkey, which is public material: they bind it to their own primary key with a Subkey Binding signature they are able to make, carrying no Key Flags and no embedded Primary Key Binding signature, which they cannot make without the subkey's private key, and a relying party verifying one of the victim's genuinely signed messages against that certificate is told the signature is valid and given the attacker's certificate as its issuer. Because a certificate's User IDs are self-asserted, a verifier that pins on the subkey's fingerprint or key ID while taking the identity from the enclosing certificate reports a real signature under an attacker-chosen identity. This is misattribution of a genuine signature rather than forgery of a new one: no private key is recovered, and the signature must be one the grafted subkey actually made. The low-level PGPSignature / PGPPublicKeyRing API performs no binding checks by design and is unaffected. Key Flags are a statement about the key the carrying signature refers to (RFC 9580 sec. 5.2.3.29), so a subkey no longer inherits them from the certificate-wide signatures of the primary key: a Subkey Binding signature that omits the subpacket now leaves the subkey with no capabilities rather than the primary's, which makes the flags the cross-certification check consults the same flags every other decision consults. Preferences and the other subpackets a direct-key signature carries are inherited as before, and the primary key itself, whose flags legitimately come from its own direct-key or User ID self-signature, is unaffected.

Improper Verification of Cryptographic Signature

Bouncy Castle Java AuthAttrs Digest Mismatch CVE-2026-71888 (before 1.86)
CVE-2026-71888 8.7 - High - October 03, 2026

In Bouncy Castle for Java before 1.86, the streaming CMS AuthenticatedData parser accepted a message whose digestAlgorithm and authAttrs fields disagreed about whether authenticated attributes were present. RFC 5652 sec. 9.1 pairs the two, requiring that authAttrs be present whenever digestAlgorithm is, and sec. 9.2 makes the MAC cover the DER encoding of authAttrs when they are present and the eContent OCTET STRING directly when they are not. CMSAuthenticatedDataParser has to choose between those two in its constructor, before it can reach authAttrs, which comes later in the SEQUENCE, so it chose on digestAlgorithm alone: for a message with digestAlgorithm absent but authAttrs present it verified the content MAC and then returned the attributes through getAuthAttrs() as though they had been authenticated, when the MAC had never covered them. An attacker able to modify a message in transit could insert an authenticated attribute, such as an RFC 2634 ESSSecurityLabel, into an otherwise valid message while holding neither the key-encryption key nor the content-MAC key, and an application taking an authorization, routing or labelling decision from those attributes would act on attacker-chosen values. The content itself remained MAC-bound. asn1.cms.AuthenticatedData now rejects the mismatched pairing when parsing and CMSAuthenticatedDataParser cross-checks the two fields once authAttrs is read. This is a variant of CVE-2026-59642, which bound the content to the MAC for messages that legitimately carry authAttrs, and which does not address this case. This issue also affects Bouncy Castle for Java LTS before 2.73.13, and Bouncy Castle for Java FIPS (BC-FJA) before bcpkix-fips 1.0.13 (1.0.X series), 2.0.13 (2.0.X series) and 2.1.13 (2.1.X series), and bcutil-fips 2.0.8 (2.0.X series) and 2.1.8 (2.1.X series).

Improper Validation of Integrity Check Value

Bouncy Castle Java PKIXCertPathReviewer nameconstraints bypass (<2.73.13)
CVE-2026-71889 8.7 - High - October 03, 2026

In Bouncy Castle for Java before 1.86, neither copy of PKIXCertPathReviewer - org.bouncycastle.pkix.jcajce.PKIXCertPathReviewer nor the legacy org.bouncycastle.x509.PKIXCertPathReviewer - applied X.509 name constraints to the end-entity certificate. checkNameConstraints walked the path with a loop bound of index greater than zero, which is the bound the CA-only steps require, but index zero is the target certificate under the standard CertPath ordering, so the permitted and excluded subtree checks of RFC 5280 sec. 6.1.3 (b) and (c) never ran against the leaf's subject DN or its subjectAltName. A chain whose leaf violated a NameConstraints extension imposed by its own issuing CA therefore reported isValidCertPath() true with an empty error list, while CertPathValidator.getInstance("PKIX", "BC"), which shares no code with the reviewer, rejected the identical chain against the identical trust anchor. An application using the reviewer to make the trust decision rather than for diagnostics alongside a real validation accepted a certificate the constrained CA was never authorised to issue. Both copies now check every certificate in the path including the target, waive the sec. 4.2.1.10 self-issued exemption for the final certificate as sec. 6.1.3 requires, and skip the sec. 6.1.4 (g) constraint-accumulation step for the target. This issue also affects Bouncy Castle for Java LTS before 2.73.13, which carries only the org.bouncycastle.pkix.jcajce copy of the reviewer. It also affects Bouncy Castle for Java FIPS (BC-FJA) before bcpkix-fips 1.0.13 (1.0.X series), 2.0.13 (2.0.X series) and 2.1.13 (2.1.X series).

Improper Certificate Validation

BC-Java <1.86: CMS Key-Transport Size Validation Bypass (JceKeyTransRecipient)
CVE-2026-71892 6.9 - Medium - October 03, 2026

In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array against the id-alg-cek-hkdf-sha256 object identifier, a comparison between a byte array and an ASN1ObjectIdentifier that is false for every possible input, so the check fell through to a key-size lookup on the outer wrapper OID. That OID identifies a key-derivation construction rather than a cipher and has no registered key size, so the size comparison was skipped entirely. A key-transport EnvelopedData or AuthEnvelopedData whose transported, HKDF-derived content-encryption key did not match the key size of the advertised content-encryption algorithm was therefore accepted even with validation explicitly enabled, silently defeating the only mechanism the API offers for enforcing recovered key size. The recipient now dispatches on the content-encryption AlgorithmIdentifier's algorithm OID, so validation checks the recovered key against the inner content-encryption algorithm. Messages with a matching key size, non-HKDF messages, and recipients that do not enable validation are unaffected. This issue also affects Bouncy Castle for Java FIPS (BC-FJA) before bcpkix-fips 2.0.13 (2.0.X series) and 2.1.13 (2.1.X series).

Incorrect Comparison

Bouncy Castle Java <1.86: OpenPGP Truncation Error in SEIPD AEAD
CVE-2026-85515 8.2 - High - October 03, 2026

In Bouncy Castle for Java before 1.86, a truncated OpenPGP encrypted message was accepted with no error reported, and on the SEIPD version 1 path with no integrity check performed at all. RFC 9580 sec. 13.7 permits an implementation to release the cleartext of the fully authenticated chunks when streaming but requires it to indicate a clear error as soon as the truncation is detected, and to report suspect integrity when it discovers malleable ciphertext. The truncation was detected and then discarded: when a message is truncated but the length field of the enclosing packet is left unchanged, BCPGInputStream.PartialInputStream raises an EOFException for the missing ciphertext, and BCPGInputStream.nextPacketTag() reports an EOFException as a clean end of message, so the packet stream above it stopped as though no packets remained. On the AEAD path (SEIPD version 2 and the version 5 AEAD packet), when the literal data packet ended on an AEAD chunk boundary and the consumer read in increments smaller than one chunk, the look-ahead for the packet after the literal triggered the truncated chunk read, so BcAEADUtil and JceAEADUtil never reached the trailing message tag of sec. 5.13.2 that authenticates the total plaintext length; the caller received the plaintext of the fully authenticated chunks, every packet following the literal was silently dropped, and no exception was raised, so a signed and encrypted message read back as a well-formed unsigned one. Every byte released on that path remained individually authenticated, making this a missing truncation error rather than a forgery, and it is a residual of CVE-2026-12817, which closed the same outcome for an attacker who corrects the outer packet length. On the SEIPD version 1 path the consequence was more serious: IntegrityProtectedInputStream verifies the modification detection code from close(), and reached close() only by closing itself when a read of it returned -1, which a truncated message never produces, so PGPEncryptedData.verify() never ran and the recipient was handed CFB-decrypted plaintext on which no integrity check of any kind had been performed. Measured on a message truncated into that shape, 136 distinct single-byte modifications of the ciphertext produced accepted, altered plaintext with no exception raised. Reachability is a property of the message rather than of attacker-supplied input: the AEAD shape held for 3 of 131 consecutive payload lengths measured, and the SEIPD version 1 shape for one payload length in sixteen, at a truncation offset that did not move with the payload length. The low-level API is unaffected, a caller that invokes PGPEncryptedData.verify() directly getting the check regardless, as are consumers reading in increments of a whole AEAD chunk or more. The AEAD decryption streams now re-throw such an EOFException as a plain IOException, which nextPacketTag() does not launder; OpenPGPMessageInputStream.close() now closes its layer's integrity-protected stream itself rather than relying on that stream having seen the end of its data; and IntegrityProtectedInputStream.close() was made idempotent, as java.io.Closeable requires, which that depends on, since the stream is genuinely closed twice on the ordinary path and PGPEncryptedData.verify() consumes the digest state behind it and cannot be run a second time. This issue also affects Bouncy Castle for Java LTS before 2.73.13, on the AEAD route only, as that edition does not ship the high-level OpenPGP API the SEIPDv1 route runs through. It also affects Bouncy Castle for Java FIPS (BC-FJA) before bcpg-fips 1.0.14 (1.0.X series), 2.0.14.1 (2.0.X series) and 2.1.14 (2.1.X series), on the AEAD route only, as those editions do not ship the high-level OpenPGP API.

Improper Validation of Integrity Check Value

Unbounded PBKDF1 Count in Bouncy Castle JCA <1.86 & <2.73.13
CVE-2026-97873 5.3 - Medium - October 03, 2026

In Bouncy Castle for Java before 1.86, the raw JCA provider's legacy PBES1 (PKCS#5 scheme 1) and PKCS#12 PBE families ran their password-based key derivation with an iteration count taken from untrusted input without bounding it, so a small input could dictate an arbitrary amount of work before anything could be verified. The AlgorithmParameters implementations (PKCS12PBE and its object identifier aliases, and PBKDF1) accepted any count from an encoded PKCS12PBEParams or PBEParameter, narrowing a value beyond the int range with intValue(), and every Cipher, Mac and SecretKeyFactory in these families derived with whatever count it was given, including one decoded by another provider's AlgorithmParameters, as when javax.crypto.EncryptedPrivateKeyInfo.getKeySpec() decrypts a PKCS#12 PBE-protected private key with BC. Both the parameter parse and the derivations now reject a negative or over-limit count under the org.bouncycastle.pbe.max_iteration_count property (default 10,000,000) that already bounded PBKDF2 (CVE-2026-17508), and the parse rejects a count beyond the int range rather than narrowing it. This issue also affects Bouncy Castle for Java LTS before 2.73.13.

Allocation of Resources Without Limits or Throttling

Bouncy Castle Java NTRU Timing Side-Channel (before 1.86)
CVE-2026-18036 8.2 - High - October 02, 2026

In Bouncy Castle for Java before 1.86, NTRU reduced secret values with the % operator in three helpers whose reference implementations are deliberately division-free, so each reduction was carried out by an integer division whose latency depends on the secret operand. Polynomial.modQ divided by a variable divisor, which a compiler cannot strength-reduce to a multiply the way it can a constant one, so it emitted a division on every call including on the decapsulation path where the dividend derives from the private key; Polynomial.mod3 and NTRUSampling.mod3 divided the secret key polynomials f and g during key generation, the message polynomials r and m during encapsulation, and coefficients recovered during decapsulation. An attacker able to measure that timing can recover information about the NTRU private key. modQ now masks, which is exact because q is always a power of two, and mod3 uses the reference implementation's division-free fold and select; the results are unchanged.

Observable Timing Discrepancy

Bouncy Castle Java before 1.86: Unbounded KDF Cost Parameters (CVE-2026-17508)
CVE-2026-17508 5.3 - Medium - October 02, 2026

In Bouncy Castle for Java before 1.86, several password-based key derivation entry points ran the KDF with cost parameters taken from the untrusted input being processed, without bounding them, so a small input could dictate an arbitrary amount of work before any password or integrity check could reject it. The affected paths are the RFC 9579 PBMAC1 MAC calculator builders, which took the PBKDF2 iteration count and derived-key length straight out of PBMAC1Params (JcePBMac1CalculatorBuilder, and PKCS12PBEUtils.createPBMac1Calculator reached from PKCS12PfxPdu.isMacValid); the scrypt parallelization parameter p in the PKCS#8 and PKCS#12 cost guards, which bounded only the cost parameter N and the block size r even though the scratch buffer scales with r times p, so the configured memory ceiling could be evaded entirely; the raw JCA PBKDF2 provider (org.bouncycastle.jcajce.provider.symmetric.PBEPBKDF2); and the bcrypt round count read from an encrypted OpenSSH v1 private key's own kdfoptions. Each now bounds the parameter before deriving, in line with the caps already applied elsewhere in the tree, with the OpenSSH round count configurable through the new org.bouncycastle.openssh.max_rounds property. This completes the bounding begun in 1.85 for the PKCS#8 / PBES2 decryptors (CVE-2026-15055). This issue also affects Bouncy Castle for Java LTS before 2.73.13, and Bouncy Castle for Java FIPS (BC-FJA) before bcpkix-fips 1.0.13 (1.0.X series), 2.0.13 (2.0.X series) and 2.1.13 (2.1.X series).

Allocation of Resources Without Limits or Throttling

Bouncy Castle Java: MLS uint32 leaf_index Signed Int Vulnerability (pre-1.86)
CVE-2026-17507 8.7 - High - October 02, 2026

In Bouncy Castle for Java before 1.86, the MLS implementation (org.bouncycastle.mls) holds RFC 9420's uint32 leaf_index in a signed int, so a wire value with the top bit set decodes to a negative number. That is a legitimate encoding rather than malformed input, and it must still decode, since the MLS interop test vectors round-trip the full range. GroupKeySet.SecretTree.hasLeaf and Group.validateRemove compared the decoded value directly against the tree's leaf count, and a signed comparison treats any negative int as less than a positive bound, so an out-of-range sender passed the membership check. In the hasLeaf case the SenderData of an unprotected PrivateMessage could then drive LeafIndex.directPath through NodeIndex.parent() arithmetic that never reaches the tree root, growing the resulting node list without bound until the JVM exhausted its heap. A single small message from any current group member could therefore deny service to every other member of the group. Both comparisons now interpret the value as unsigned via Integer.toUnsignedLong, rejecting an out-of-range sender however it was encoded; well-formed leaf indices are unaffected.

Signed to Unsigned Conversion Error

Bouncy Castle Java OOM via unbounded read before v1.85
CVE-2026-14682 8.7 - High - August 03, 2026

In Bouncy Castle for Java before 1.85, Possible OOM from unbounded up-front allocation on a definite-length read. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bc-fips 1.0.2.7 (1.0.X series), 2.0.2 (2.0.X series) and 2.1.3 (2.1.X series), and before bctls-fips 1.0.24.

Stack Exhaustion

Bouncy Castle JSSE HV CN-Fallback default enabled CVE-2026-59638 (pre-1.85)
CVE-2026-59638 9.3 - Critical - August 03, 2026

In Bouncy Castle for Java before 1.85, JSSE hostname verifier CN-fallback enabled by default despite documented opt-in. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bctls-fips 1.0.24 (1.0.X series), 2.0.24 (2.0.X series) and 2.1.24 (2.1.X series).

Improper Validation of Certificate with Host Mismatch

Bouncy Castle BKS/UBER Keystore OOB Length Allocation <1.85, <2.73.12
CVE-2026-12185 7.1 - High - August 03, 2026

In Bouncy Castle for Java before 1.85, BKS/UBER keystore allocates from untrusted lengths before integrity check. This issue also affects Bouncy Castle for Java LTS before 2.73.12.

Stack Exhaustion

Bouncy Castle Java: Name Constraints Bypass via Trailing Dot in rfc822Name/URI ( 1.85, 2.73.12, 2.
CVE-2026-8763 9.3 - Critical - August 03, 2026

In Bouncy Castle for Java before 1.85, Name Constraints bypass via trailing dot in rfc822Name and URI. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bc-fips 1.0.2.7 (1.0.X series), 2.0.2 (2.0.X series) and 2.1.3 (2.1.X series).

Improper Certificate Validation

Timing Leak in BouncyCastle v1.73-1.77 Kyber ML-KEM (Poly.toMsg & Compression)
CVE-2024-14041 8.2 - High - July 28, 2026

In Bouncy Castle for Java from 1.73 to before 1.78, three ML-KEM (CRYSTALS-Kyber) routines divided secret-derived polynomial coefficients by the modulus q: Poly.toMsg, which decodes the decrypted message, and the ciphertext compression routines Poly.compressPoly and PolyVec.compressPolyVec. An attacker able to measure the timing of a large number of decapsulations performed with the same long-term private key can recover that key. These are the KyberSlash1 (Poly.toMsg) and KyberSlash2 (ciphertext compression) divisions. Compression performed during encapsulation operates on values that become the public ciphertext and is not affected.

Observable Timing Discrepancy

BC-JAVA bcpg <=1.83 UNBOUND PGP AEAD CHUNK Resource Exhaustion
CVE-2026-3505 7.5 - High - April 15, 2026

Allocation of resources without limits or throttling, Uncontrolled Resource Consumption vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA bcpg on all (pg modules). This vulnerability is associated with program files AEADEncDataPacket.Java, BcAEADUtil.Java, JceAEADUtil.Java, OperatorHelper.Java. This issue affects BC-JAVA: from 1.74 before 1.80.2, from 1.81 before 1.81.1, from 1.82 before 1.84.

Allocation of Resources Without Limits or Throttling

BC-JAVA bcpkix 1.491.83: Empty Signature Vulnerability in PKIX CompositeVerifier
CVE-2026-5588 7.5 - High - April 15, 2026

Use of a Broken or Risky Cryptographic Algorithm vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA bcpkix on all (pkix modules), Legion of the Bouncy Castle Inc. BCPKIX-FIPS bcpkix on All (pkix modules), Legion of the Bouncy Castle Inc. BCPIX-LTS bcpkix on All (pkix modules). This vulnerability is associated with program files JcaContentVerifierProviderBuilder.Java, JcaContentVerfierProviderBuilder.Java. This issue affects BC-JAVA: from 1.67 before 1.80.2, from 1.81 before 1.81.1, from 1.82 before 1.84; BCPKIX-FIPS: from 2.0.6 before 2.0.11, from 2.1.7 before 2.1.11; BCPIX-LTS: from 2.73.7 before 2.73.11.

Use of a Broken or Risky Cryptographic Algorithm

CVE-2026-5598: BC-JAVA core (<1.84) timing channel leak FrodoKEM
CVE-2026-5598 7.5 - High - April 15, 2026

Covert timing channel vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA core on all (core modules). This vulnerability is associated with program files FrodoEngine.Java. This issue affects BC-JAVA: from 1.71 before 1.80.2, from 1.81 before 1.81.1, from 1.82 before 1.84.

Covert Timing Channel

LDAP Injection in Bouncy Castle bcprov 1.741.84 (LDAPStoreHelper)
CVE-2026-0636 6.5 - Medium - April 15, 2026

Improper neutralization of special elements used in an LDAP query ('LDAP injection') vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA bcprov on all (prov modules). This vulnerability is associated with program files LDAPStoreHelper. This issue affects BC-JAVA: from 1.74 before 1.80.2, from 1.81 before 1.81.1, from 1.82 before 1.84.

LDAP Injection

Broken GOSTCTR Algorithm in Bouncy Castle BC-Java bcprov <1.84
CVE-2025-14813 7.5 - High - April 15, 2026

: Use of a Broken or Risky Cryptographic Algorithm vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA bcprov on all (core modules). This vulnerability is associated with program files G3413CTRBlockCipher. This issue affects BC-JAVA: from 1.59 before 1.80.2, from 1.81 before 1.81.1, from 1.82 before 1.84.

Use of a Broken or Risky Cryptographic Algorithm

Bouncy Castle Java API Resource Exhaustion (1.44-1.78, FIPS 1.0.0-2.0.7)
CVE-2025-8916 - August 13, 2025

Allocation of Resources Without Limits or Throttling vulnerability in Legion of the Bouncy Castle Inc. BC Java bcpkix on All (API modules), Legion of the Bouncy Castle Inc. BC Java bcprov on All (API modules), Legion of the Bouncy Castle Inc. BCPKIX FIPS bcpkix-fips on All (API modules) allows Excessive Allocation. This vulnerability is associated with program files https://github.Com/bcgit/bc-java/blob/main/pkix/src/main/java/org/bouncycastle/pkix/jcajce/PKIXCertPathReviewer.Java, https://github.Com/bcgit/bc-java/blob/main/prov/src/main/java/org/bouncycastle/x509/PKIXCertPathReviewer.Java. This issue affects BC Java: from 1.44 through 1.78; BC Java: from 1.44 through 1.78; BCPKIX FIPS: from 1.0.0 through 1.0.7, from 2.0.0 through 2.0.7.

Allocation of Resources Without Limits or Throttling

Bouncy Castle Java DoS via Unbounded Allocation in ASN1ObjId (1.0-1.77)
CVE-2025-8885 - August 12, 2025

Allocation of Resources Without Limits or Throttling vulnerability in Legion of the Bouncy Castle Inc. BC Java bcprov on All (API modules), Legion of the Bouncy Castle Inc. BC-FJA bc-fips on All allows Excessive Allocation. This vulnerability is associated with program files https://github.com/bcgit/bc-java/blob/main/core/src/main/java/org/bouncycastle/asn1/ASN1ObjectIdenti... https://github.com/bcgit/bc-java/blob/main/core/src/main/java/org/bouncycastle/asn1/ASN1ObjectIdentifier.Java . This issue affects BC Java: from 1.0 through 1.77; BC-FJA: from 1.0.0 through 1.0.2.5, from 2.0.0 through 2.0.1.

Allocation of Resources Without Limits or Throttling

Bouncy Castle Java LDAP Injection via CertStore (pre-1.74)
CVE-2023-33201 5.3 - Medium - July 05, 2023

Bouncy Castle For Java before 1.74 is affected by an LDAP injection vulnerability. The vulnerability only affects applications that use an LDAP CertStore from Bouncy Castle to validate X.509 certificates. During the certificate validation process, Bouncy Castle inserts the certificate's Subject Name into an LDAP search filter without any escaping, which leads to an LDAP injection vulnerability.

Improper Certificate Validation

An issue was discovered in Legion of the Bouncy Castle BC Java 1.65 and 1.66
CVE-2020-28052 8.1 - High - December 18, 2020

An issue was discovered in Legion of the Bouncy Castle BC Java 1.65 and 1.66. The OpenBSDBCrypt.checkPassword utility method compared incorrect data when checking the password, allowing incorrect passwords to indicate they were matching with previously hashed ones that were different.

The ASN.1 parser in Bouncy Castle Crypto (aka BC Java) 1.63 can trigger a large attempted memory allocation, and resultant OutOfMemoryError error
CVE-2019-17359 - October 08, 2019

The ASN.1 parser in Bouncy Castle Crypto (aka BC Java) 1.63 can trigger a large attempted memory allocation, and resultant OutOfMemoryError error, via crafted ASN.1 data. This is fixed in 1.64.

Legion of the Bouncy Castle Legion of the Bouncy Castle Java Cryptography APIs 1.58 up to but not including 1.60 contains a CWE-470: Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') vulnerability in XMSS/XMSS^MT private key deserialization
CVE-2018-1000613 9.8 - Critical - July 09, 2018

Legion of the Bouncy Castle Legion of the Bouncy Castle Java Cryptography APIs 1.58 up to but not including 1.60 contains a CWE-470: Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') vulnerability in XMSS/XMSS^MT private key deserialization that can result in Deserializing an XMSS/XMSS^MT private key can result in the execution of unexpected code. This attack appear to be exploitable via A handcrafted private key can include references to unexpected classes which will be picked up from the class path for the executing application. This vulnerability appears to have been fixed in 1.60 and later.

Reflection Injection

Bouncy Castle BC 1.54 - 1.59
CVE-2018-1000180 7.5 - High - June 05, 2018

Bouncy Castle BC 1.54 - 1.59, BC-FJA 1.0.0, BC-FJA 1.0.1 and earlier have a flaw in the Low-level interface to RSA key pair generator, specifically RSA Key Pairs generated in low-level API with added certainty may have less M-R tests than expected. This appears to be fixed in versions BC 1.60 beta 4 and later, BC-FJA 1.0.2 and later.

Use of a Broken or Risky Cryptographic Algorithm

In the Bouncy Castle JCE Provider version 1.55 and earlier the DHIES implementation allowed the use of ECB mode
CVE-2016-1000344 7.4 - High - June 04, 2018

In the Bouncy Castle JCE Provider version 1.55 and earlier the DHIES implementation allowed the use of ECB mode. This mode is regarded as unsafe and support for it has been removed from the provider.

Cryptographic Issues

In the Bouncy Castle JCE Provider version 1.55 and earlier the DHIES/ECIES CBC mode vulnerable to padding oracle attack
CVE-2016-1000345 5.9 - Medium - June 04, 2018

In the Bouncy Castle JCE Provider version 1.55 and earlier the DHIES/ECIES CBC mode vulnerable to padding oracle attack. For BC 1.55 and older, in an environment where timings can be easily observed, it is possible with enough observations to identify when the decryption is failing due to padding.

7PK - Time and State

In the Bouncy Castle JCE Provider version 1.55 and earlier the other party DH public key is not fully validated
CVE-2016-1000346 3.7 - Low - June 04, 2018

In the Bouncy Castle JCE Provider version 1.55 and earlier the other party DH public key is not fully validated. This can cause issues as invalid keys can be used to reveal details about the other party's private key where static Diffie-Hellman is in use. As of release 1.56 the key parameters are checked on agreement calculation.

Key Management Errors

In the Bouncy Castle JCE Provider version 1.55 and earlier the ECIES implementation allowed the use of ECB mode
CVE-2016-1000352 7.4 - High - June 04, 2018

In the Bouncy Castle JCE Provider version 1.55 and earlier the ECIES implementation allowed the use of ECB mode. This mode is regarded as unsafe and support for it has been removed from the provider.

Cryptographic Issues

In the Bouncy Castle JCE Provider version 1.55 and earlier the primary engine class used for AES was AESFastEngine
CVE-2016-1000339 5.3 - Medium - June 04, 2018

In the Bouncy Castle JCE Provider version 1.55 and earlier the primary engine class used for AES was AESFastEngine. Due to the highly table driven approach used in the algorithm it turns out that if the data channel on the CPU can be monitored the lookup table accesses are sufficient to leak information on the AES key being used. There was also a leak in AESEngine although it was substantially less. AESEngine has been modified to remove any signs of leakage (testing carried out on Intel X86-64) and is now the primary AES class for the BC JCE provider from 1.56. Use of AESFastEngine is now only recommended where otherwise deemed appropriate.

Cryptographic Issues

In the Bouncy Castle JCE Provider versions 1.51 to 1.55
CVE-2016-1000340 7.5 - High - June 04, 2018

In the Bouncy Castle JCE Provider versions 1.51 to 1.55, a carry propagation bug was introduced in the implementation of squaring for several raw math classes have been fixed (org.bouncycastle.math.raw.Nat???). These classes are used by our custom elliptic curve implementations (org.bouncycastle.math.ec.custom.**), so there was the possibility of rare (in general usage) spurious calculations for elliptic curve scalar multiplications. Such errors would have been detected with high probability by the output validation for our scalar multipliers.

Data Processing Errors

In the Bouncy Castle JCE Provider version 1.55 and earlier DSA signature generation is vulnerable to timing attack
CVE-2016-1000341 5.9 - Medium - June 04, 2018

In the Bouncy Castle JCE Provider version 1.55 and earlier DSA signature generation is vulnerable to timing attack. Where timings can be closely observed for the generation of signatures, the lack of blinding in 1.55, or earlier, may allow an attacker to gain information about the signature's k value and ultimately the private value as well.

7PK - Time and State

In the Bouncy Castle JCE Provider version 1.55 and earlier ECDSA does not fully validate ASN.1 encoding of signature on verification
CVE-2016-1000342 7.5 - High - June 04, 2018

In the Bouncy Castle JCE Provider version 1.55 and earlier ECDSA does not fully validate ASN.1 encoding of signature on verification. It is possible to inject extra elements in the sequence making up the signature and still have it validate, which in some cases may allow the introduction of 'invisible' data into a signed structure.

Improper Verification of Cryptographic Signature

In the Bouncy Castle JCE Provider version 1.55 and earlier the DSA key pair generator generates a weak private key if used with default values
CVE-2016-1000343 7.5 - High - June 04, 2018

In the Bouncy Castle JCE Provider version 1.55 and earlier the DSA key pair generator generates a weak private key if used with default values. If the JCA key pair generator is not explicitly initialised with DSA parameters, 1.55 and earlier generates a private value assuming a 1024 bit key size. In earlier releases this can be dealt with by explicitly passing parameters to the key pair generator.

Cryptographic Issues

The default BKS keystore use an HMAC that is only 16 bits long, which can allow an attacker to compromise the integrity of a BKS keystore
CVE-2018-5382 4.4 - Medium - April 16, 2018

The default BKS keystore use an HMAC that is only 16 bits long, which can allow an attacker to compromise the integrity of a BKS keystore. Bouncy Castle release 1.47 changes the BKS format to a format which uses a 160 bit HMAC instead. This applies to any BKS keystore generated prior to BC 1.47. For situations where people need to create the files for legacy reasons a specific keystore type "BKS-V1" was introduced in 1.49. It should be noted that the use of "BKS-V1" is discouraged by the library authors and should only be used where it is otherwise safe to do so, as in where the use of a 16 bit checksum for the file integrity check is not going to cause a security issue in itself.

Improper Validation of Integrity Check Value