Bouncy Castle CMS AuthEnvelopedData Tag-Len Byp <1.85, <2.73.12, <1.0.12FIPS
CVE-2026-12802 Published on August 3, 2026

CMS AuthEnvelopedData fails to enforce tag-length on decryption
In Bouncy Castle for Java before 1.85, CMS AuthEnvelopedData fails to enforce tag-length on decryption. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bcpkix-fips 1.0.12 (1.0.X series), 2.0.12 (2.0.X series) and 2.1.12 (2.1.X series).

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-12802 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE

Weakness Type

Improper Validation of Integrity Check Value

The software does not validate or incorrectly validates the integrity check values or "checksums" of a message. This may prevent it from detecting if the data has been modified or corrupted in transmission. Improper validation of checksums before use results in an unnecessary risk that can easily be mitigated. The protocol specification describes the algorithm used for calculating the checksum. It is then a simple matter of implementing the calculation and verifying that the calculated checksum and the received checksum match. Improper verification of the calculated checksum and the received checksum can lead to far greater consequences.


Affected Versions

Legion of the Bouncy Castle Inc. BC-JAVA: Legion of the Bouncy Castle Inc. BC-LTS-JAVA: Legion of the Bouncy Castle Inc. BC-FJA:

Exploit Probability

EPSS
0.15%
Percentile
3.30%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.