Missing cryptographic step in the DSTU 7624 CCM mode implementation (KCcmBlockCipher) in Legion of the Bouncy Castle Inc. (CVE-2026-16000)
A vulnerability in the DSTU 7624 CCM mode implementation (KCcmBlockCipher) in Legion of the Bouncy Castle Inc. bc-csharp before version 2.7.0 allows attackers who can observe encrypted messages without associated data to forge ciphertexts with valid authentication tags. This occurs because a critical cryptographic step binding the nonce, message length, and parameter flags into the CBC-MAC was skipped when no associated data was present. Only applications using KCcmBlockCipher directly without associated data are affected.
AI Analysis
Technical Summary
The DSTU 7624 CCM mode implementation (KCcmBlockCipher) in Legion of the Bouncy Castle Inc. bc-csharp prior to 2.7.0 contains a cryptographic flaw where the G1 block, which binds the nonce, message length, and parameter flags into the CBC-MAC, is processed only if associated data is present. When no associated data is supplied, the authentication tag is computed as a CBC-MAC of the plaintext alone, independent of the nonce. This allows an attacker who can observe encrypted messages of known or chosen content to forge ciphertexts with valid authentication tags. The vulnerability affects only applications that use KCcmBlockCipher directly and do not supply associated data.
Potential Impact
An attacker capable of observing encrypted messages without associated data can forge ciphertexts with valid authentication tags, potentially compromising message integrity and authenticity. This undermines the cryptographic guarantees of the CCM mode in affected versions, allowing forgery attacks. However, the vulnerability does not affect applications that use associated data or do not use KCcmBlockCipher directly.
Mitigation Recommendations
A fix is available in Legion of the Bouncy Castle Inc. bc-csharp version 2.7.0 and later. Users should upgrade to version 2.7.0 or newer to remediate this vulnerability. Until then, applications should avoid using KCcmBlockCipher without associated data. Patch status is not explicitly confirmed in the provided data, so users should verify the vendor advisory for the latest remediation guidance.
Missing cryptographic step in the DSTU 7624 CCM mode implementation (KCcmBlockCipher) in Legion of the Bouncy Castle Inc. (CVE-2026-16000)
Description
A vulnerability in the DSTU 7624 CCM mode implementation (KCcmBlockCipher) in Legion of the Bouncy Castle Inc. bc-csharp before version 2.7.0 allows attackers who can observe encrypted messages without associated data to forge ciphertexts with valid authentication tags. This occurs because a critical cryptographic step binding the nonce, message length, and parameter flags into the CBC-MAC was skipped when no associated data was present. Only applications using KCcmBlockCipher directly without associated data are affected.
CVSS v4.0
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The DSTU 7624 CCM mode implementation (KCcmBlockCipher) in Legion of the Bouncy Castle Inc. bc-csharp prior to 2.7.0 contains a cryptographic flaw where the G1 block, which binds the nonce, message length, and parameter flags into the CBC-MAC, is processed only if associated data is present. When no associated data is supplied, the authentication tag is computed as a CBC-MAC of the plaintext alone, independent of the nonce. This allows an attacker who can observe encrypted messages of known or chosen content to forge ciphertexts with valid authentication tags. The vulnerability affects only applications that use KCcmBlockCipher directly and do not supply associated data.
Potential Impact
An attacker capable of observing encrypted messages without associated data can forge ciphertexts with valid authentication tags, potentially compromising message integrity and authenticity. This undermines the cryptographic guarantees of the CCM mode in affected versions, allowing forgery attacks. However, the vulnerability does not affect applications that use associated data or do not use KCcmBlockCipher directly.
Mitigation Recommendations
A fix is available in Legion of the Bouncy Castle Inc. bc-csharp version 2.7.0 and later. Users should upgrade to version 2.7.0 or newer to remediate this vulnerability. Until then, applications should avoid using KCcmBlockCipher without associated data. Patch status is not explicitly confirmed in the provided data, so users should verify the vendor advisory for the latest remediation guidance.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-m3jv-gj9x-qwrv
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-16000"]
- Database Specific Severity
- HIGH
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6abfeebca43b0b3b89e5660a
Added to database: 10/02/2026, 17:49:48 UTC
Last enriched: 10/02/2026, 18:23:03 UTC
Last updated: 10/02/2026, 18:45:56 UTC
Views: 2
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