Gnutls

GnuTLS DoS via oversized SANs in certificates
CVE-2025-14831 5.3 - Medium - February 09, 2026

A flaw was found in GnuTLS. This vulnerability allows a denial of service (DoS) by excessive CPU (Central Processing Unit) and memory consumption via specially crafted malicious certificates containing a large number of name constraints and subject alternative names (SANs).

Inefficient Algorithmic Complexity

GnuTLS certtool Heap OOB Null Write in Template Parsing – DoS
CVE-2025-32990 6.5 - Medium - July 10, 2025

A heap-buffer-overflow (off-by-one) flaw was found in the GnuTLS software in the template parsing logic within the certtool utility. When it reads certain settings from a template file, it allows an attacker to cause an out-of-bounds (OOB) NULL pointer write, resulting in memory corruption and a denial-of-service (DoS) that could potentially crash the system.

Heap-based Buffer Overflow

GnuTLS CT SCT Heap-Buffer-Overread (CVE-2025-32989)
CVE-2025-32989 5.3 - Medium - July 10, 2025

A heap-buffer-overread vulnerability was found in GnuTLS in how it handles the Certificate Transparency (CT) Signed Certificate Timestamp (SCT) extension during X.509 certificate parsing. This flaw allows a malicious user to create a certificate containing a malformed SCT extension (OID 1.3.6.1.4.1.11129.2.4.2) that contains sensitive data. This issue leads to the exposure of confidential information when GnuTLS verifies certificates from certain websites when the certificate (SCT) is not checked correctly.

Improper Certificate Validation

GnuTLS Minerva Timing Side-Channel via GNUTLS_PRIVKEY_FLAG_REPRODUCIBLE
CVE-2024-28834 5.3 - Medium - March 21, 2024

A flaw was found in GnuTLS. The Minerva attack is a cryptographic vulnerability that exploits deterministic behavior in systems like GnuTLS, leading to side-channel leaks. In specific scenarios, such as when using the GNUTLS_PRIVKEY_FLAG_REPRODUCIBLE flag, it can result in a noticeable step in nonce size from 513 to 512 bits, exposing a potential timing side-channel.

Use of a Broken or Risky Cryptographic Algorithm

GnuTLS: DoS via Faulty Certificate Chain Validation in Cockpit
CVE-2024-0567 7.5 - High - January 16, 2024

A vulnerability was found in GnuTLS, where a cockpit (which uses gnuTLS) rejects a certificate chain with distributed trust. This issue occurs when validating a certificate chain with cockpit-certificate-ensure. This flaw allows an unauthenticated, remote client or attacker to initiate a denial of service attack.

Improper Verification of Cryptographic Signature

GnuTLS timing attack via RSA-PSK ClientKeyExchange (CVE-2024-0553)
CVE-2024-0553 7.5 - High - January 16, 2024

A vulnerability was found in GnuTLS. The response times to malformed ciphertexts in RSA-PSK ClientKeyExchange differ from the response times of ciphertexts with correct PKCS#1 v1.5 padding. This issue may allow a remote attacker to perform a timing side-channel attack in the RSA-PSK key exchange, potentially leading to the leakage of sensitive data. CVE-2024-0553 is designated as an incomplete resolution for CVE-2023-5981.

Side Channel Attack

OpenSSL RSA-PSK ClientKeyExchange timing side channel
CVE-2023-5981 5.9 - Medium - November 28, 2023

A vulnerability was found that the response times to malformed ciphertexts in RSA-PSK ClientKeyExchange differ from response times of ciphertexts with correct PKCS#1 v1.5 padding.

Side Channel Attack

Timing Side-Channel: RSA ClientKeyExchange Decryption in GnuTLS
CVE-2023-0361 7.4 - High - February 15, 2023

A timing side-channel in the handling of RSA ClientKeyExchange messages was discovered in GnuTLS. This side-channel can be sufficient to recover the key encrypted in the RSA ciphertext across a network in a Bleichenbacher style attack. To achieve a successful decryption the attacker would need to send a large amount of specially crafted messages to the vulnerable server. By recovering the secret from the ClientKeyExchange message, the attacker would be able to decrypt the application data exchanged over that connection.

Side Channel Attack

Null Pointer Deref in GnuTLS Nettle Hash Leading DoS
CVE-2021-4209 6.5 - Medium - August 24, 2022

A NULL pointer dereference flaw was found in GnuTLS. As Nettle's hash update functions internally call memcpy, providing zero-length input may cause undefined behavior. This flaw leads to a denial of service after authentication in rare circumstances.

NULL Pointer Dereference

GnuTLS Double Free in pkcs7 Verification (CVE-2022-2509)
CVE-2022-2509 7.5 - High - August 01, 2022

A vulnerability found in gnutls. This security flaw happens because of a double free error occurs during verification of pkcs7 signatures in gnutls_pkcs7_verify function.

Double-free

A flaw was found in gnutls
CVE-2021-20231 - March 12, 2021

A flaw was found in gnutls. A use after free issue in client sending key_share extension may lead to memory corruption and other consequences.

Dangling pointer

A flaw was found in gnutls
CVE-2021-20232 9.8 - Critical - March 12, 2021

A flaw was found in gnutls. A use after free issue in client_send_params in lib/ext/pre_shared_key.c may lead to memory corruption and other potential consequences.

Dangling pointer

An issue was discovered in GnuTLS before 3.6.15
CVE-2020-24659 7.5 - High - September 04, 2020

An issue was discovered in GnuTLS before 3.6.15. A server can trigger a NULL pointer dereference in a TLS 1.3 client if a no_renegotiation alert is sent with unexpected timing, and then an invalid second handshake occurs. The crash happens in the application's error handling path, where the gnutls_deinit function is called after detecting a handshake failure.

Memory Corruption

GnuTLS 3.6.x before 3.6.14 uses incorrect cryptography for encrypting a session ticket (a loss of confidentiality in TLS 1.2
CVE-2020-13777 7.4 - High - June 04, 2020

GnuTLS 3.6.x before 3.6.14 uses incorrect cryptography for encrypting a session ticket (a loss of confidentiality in TLS 1.2, and an authentication bypass in TLS 1.3). The earliest affected version is 3.6.4 (2018-09-24) because of an error in a 2018-09-18 commit. Until the first key rotation, the TLS server always uses wrong data in place of an encryption key derived from an application.

Use of a Broken or Risky Cryptographic Algorithm

GnuTLS 3.6.x before 3.6.13 uses incorrect cryptography for DTLS
CVE-2020-11501 - April 03, 2020

GnuTLS 3.6.x before 3.6.13 uses incorrect cryptography for DTLS. The earliest affected version is 3.6.3 (2018-07-16) because of an error in a 2017-10-06 commit. The DTLS client always uses 32 '\0' bytes instead of a random value, and thus contributes no randomness to a DTLS negotiation. This breaks the security guarantees of the DTLS protocol.

It was discovered in gnutls before version 3.6.7 upstream
CVE-2019-3836 7.5 - High - April 01, 2019

It was discovered in gnutls before version 3.6.7 upstream that there is an uninitialized pointer access in gnutls versions 3.6.3 or later which can be triggered by certain post-handshake messages.

Access of Uninitialized Pointer

A vulnerability was found in gnutls versions from 3.5.8 before 3.6.7
CVE-2019-3829 7.5 - High - March 27, 2019

A vulnerability was found in gnutls versions from 3.5.8 before 3.6.7. A memory corruption (double free) vulnerability in the certificate verification API. Any client or server application that verifies X.509 certificates with GnuTLS 3.5.8 or later is affected.

Double-free

A Bleichenbacher type side-channel based padding oracle attack was found in the way gnutls handles verification of RSA decrypted PKCS#1 v1.5 data
CVE-2018-16868 5.6 - Medium - December 03, 2018

A Bleichenbacher type side-channel based padding oracle attack was found in the way gnutls handles verification of RSA decrypted PKCS#1 v1.5 data. An attacker who is able to run process on the same physical core as the victim process, could use this to extract plaintext or in some cases downgrade any TLS connections to a vulnerable server.

Side Channel Attack

A cache-based side channel in GnuTLS implementation that leads to plain text recovery in cross-VM attack setting was found
CVE-2018-10846 - August 22, 2018

A cache-based side channel in GnuTLS implementation that leads to plain text recovery in cross-VM attack setting was found. An attacker could use a combination of "Just in Time" Prime+probe attack in combination with Lucky-13 attack to recover plain text using crafted packets.

Covert Timing Channel

It was found that the GnuTLS implementation of HMAC-SHA-256 was vulnerable to a Lucky thirteen style attack
CVE-2018-10844 - August 22, 2018

It was found that the GnuTLS implementation of HMAC-SHA-256 was vulnerable to a Lucky thirteen style attack. Remote attackers could use this flaw to conduct distinguishing attacks and plaintext-recovery attacks via statistical analysis of timing data using crafted packets.

Covert Timing Channel

It was found that the GnuTLS implementation of HMAC-SHA-384 was vulnerable to a Lucky thirteen style attack
CVE-2018-10845 - August 22, 2018

It was found that the GnuTLS implementation of HMAC-SHA-384 was vulnerable to a Lucky thirteen style attack. Remote attackers could use this flaw to conduct distinguishing attacks and plain text recovery attacks via statistical analysis of timing data using crafted packets.

Covert Timing Channel

The "GNUTLS_KEYLOGFILE" environment variable in gnutls 3.4.12
CVE-2016-4456 - August 08, 2017

The "GNUTLS_KEYLOGFILE" environment variable in gnutls 3.4.12 allows remote attackers to overwrite and corrupt arbitrary files in the filesystem.

GnuTLS before 2.9.10 does not verify the activation and expiration dates of CA certificates, which allows man-in-the-middle attackers to spoof servers via a certificate issued by a CA certificate
CVE-2014-8155 - August 14, 2015

GnuTLS before 2.9.10 does not verify the activation and expiration dates of CA certificates, which allows man-in-the-middle attackers to spoof servers via a certificate issued by a CA certificate that is (1) not yet valid or (2) no longer valid.

DEPRECATED: Code

Buffer overflow in the read_server_hello function in lib/gnutls_handshake.c in GnuTLS before 3.1.25, 3.2.x before 3.2.15, and 3.3.x before 3.3.4
CVE-2014-3466 - June 03, 2014

Buffer overflow in the read_server_hello function in lib/gnutls_handshake.c in GnuTLS before 3.1.25, 3.2.x before 3.2.15, and 3.3.x before 3.3.4 allows remote servers to cause a denial of service (memory corruption) or possibly execute arbitrary code via a long session id in a ServerHello message.

The _gnutls_ciphertext2compressed function in lib/gnutls_cipher.c in GnuTLS 2.12.23
CVE-2013-2116 - July 03, 2013

The _gnutls_ciphertext2compressed function in lib/gnutls_cipher.c in GnuTLS 2.12.23 allows remote attackers to cause a denial of service (buffer over-read and crash) via a crafted padding length. NOTE: this might be due to an incorrect fix for CVE-2013-0169.

Improper Input Validation

The _gnutls_x509_oid2mac_algorithm function in lib/gnutls_algorithms.c in GnuTLS before 1.4.2 allows remote attackers to cause a denial of service (crash) via a crafted X.509 certificate
CVE-2006-7239 - May 24, 2010

The _gnutls_x509_oid2mac_algorithm function in lib/gnutls_algorithms.c in GnuTLS before 1.4.2 allows remote attackers to cause a denial of service (crash) via a crafted X.509 certificate that uses a hash algorithm that is not supported by GnuTLS, which triggers a NULL pointer dereference.

Cryptographic Issues

The TLS protocol, and the SSL protocol 3.0 and possibly earlier, as used in Microsoft Internet Information Services (IIS) 7.0, mod_ssl in the Apache HTTP Server 2.2.14 and earlier, OpenSSL before 0.9.8l, GnuTLS 2.8.5 and earlier, Mozilla Network Security Services (NSS) 3.12.4 and earlier, multiple Cisco products, and other products, does not properly associate renegotiation handshakes with an existing connection, which allows man-in-the-middle attackers to insert data into HTTPS sessions, and possibly other types of sessions protected by TLS or SSL, by sending an unauthenticated request
CVE-2009-3555 - November 09, 2009

The TLS protocol, and the SSL protocol 3.0 and possibly earlier, as used in Microsoft Internet Information Services (IIS) 7.0, mod_ssl in the Apache HTTP Server 2.2.14 and earlier, OpenSSL before 0.9.8l, GnuTLS 2.8.5 and earlier, Mozilla Network Security Services (NSS) 3.12.4 and earlier, multiple Cisco products, and other products, does not properly associate renegotiation handshakes with an existing connection, which allows man-in-the-middle attackers to insert data into HTTPS sessions, and possibly other types of sessions protected by TLS or SSL, by sending an unauthenticated request that is processed retroactively by a server in a post-renegotiation context, related to a "plaintext injection" attack, aka the "Project Mogul" issue.

Improper Certificate Validation

The Network Security Services (NSS) library before 3.12.3, as used in Firefox; GnuTLS before 2.6.4 and 2.7.4; OpenSSL 0.9.8 through 0.9.8k; and other products support MD2 with X.509 certificates, which might
CVE-2009-2409 - July 30, 2009

The Network Security Services (NSS) library before 3.12.3, as used in Firefox; GnuTLS before 2.6.4 and 2.7.4; OpenSSL 0.9.8 through 0.9.8k; and other products support MD2 with X.509 certificates, which might allow remote attackers to spoof certificates by using MD2 design flaws to generate a hash collision in less than brute-force time. NOTE: the scope of this issue is currently limited because the amount of computation required is still large.

lib/pk-libgcrypt.c in libgnutls in GnuTLS before 2.6.6 does not properly handle invalid DSA signatures, which allows remote attackers to cause a denial of service (application crash) and possibly have unspecified other impact via a malformed DSA key
CVE-2009-1415 - April 30, 2009

lib/pk-libgcrypt.c in libgnutls in GnuTLS before 2.6.6 does not properly handle invalid DSA signatures, which allows remote attackers to cause a denial of service (application crash) and possibly have unspecified other impact via a malformed DSA key that triggers a (1) free of an uninitialized pointer or (2) double free.

Access of Uninitialized Pointer

The _gnutls_x509_verify_certificate function in lib/x509/verify.c in libgnutls in GnuTLS before 2.6.1 trusts certificate chains in which the last certificate is an arbitrary trusted, self-signed certificate, which
CVE-2008-4989 5.9 - Medium - November 13, 2008

The _gnutls_x509_verify_certificate function in lib/x509/verify.c in libgnutls in GnuTLS before 2.6.1 trusts certificate chains in which the last certificate is an arbitrary trusted, self-signed certificate, which allows man-in-the-middle attackers to insert a spoofed certificate for any Distinguished Name (DN).

Improper Certificate Validation