CVE-2026-16000: Legion Of The Bouncy Castle Inc Bc-Csharp

High severity, CVSS 8.7. EPSS: 0.3% chance of exploitation in the next 30 days.

Missing cryptographic step in the DSTU 7624 CCM mode implementation (KCcmBlockCipher) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who can observe encrypted messages of known or chosen content to forge ciphertexts with valid authentication tags, via messages encrypted without associated data. The cause is that the G1 block, which binds the nonce, the message length and the parameter flags into the CBC-MAC, was processed only when associated data was present. Without associated data the tag was a CBC-MAC of the plaintext alone, independent of the nonce. Only applications that use KCcmBlockCipher directly and supply no associated data are affected.

Affected products

• Legion Of The Bouncy Castle Inc Bc-Csharp: before 2.7.0 (fixed in 2.7.0)

Published 2026-10-02. Last modified 2026-10-02.