CVE-2026-103601

Release of unverified plaintext in the CCM (CcmBlockCipher) and DSTU 7624 CCM (KCcmBlockCipher) AEAD modes in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote attacker to obtain decryptions of ciphertexts of their choosing via forged messages sent to an application that lets the output buffer of a failed decryption be observed, for example through buffer reuse or logging, because decryption wrote the recovered plaintext into the caller-supplied output buffer before checking the authentication tag and left it there when the check failed. Only decryption into a caller-supplied buffer is affected; methods that return a newly allocated array are not.

Score

CVSS 4.0 8.2 High

Status

Analyzed - 91579145-5d7b-4cc5-b925-a0262ff19630

Published

2026-10-02

Last modified

2026-10-28

Weaknesses

CWE-354

Affected products

• Bc-csharp (Bouncycastle)
• Bc-csharp (Legion Of The Bouncy Castle Inc.)

References

• https://github.com/bcgit/bc-csharp/wiki/CVE-2026-103601
• https://github.com/bcgit/bc-csharp/commit/e0868323645a063cb2479646e93c1449dc338de5
• https://github.com/bcgit/bc-csharp/commit/4ddb1d0bfeae3a81b18f4446d8cc8a7871bd2d9f