Release of unverified plaintext in the CCM (CcmBlockCipher) and DSTU 7624 CCM (KCcmBlockCipher)…

Why it is Yellow

• CVSS 8.2 high
• Remotely exploitable without logging in

References

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

Original description

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.