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.
Metrics
Affected Vendors & Products
References
History
Tue, 27 Oct 2026 16:45:00 +0000
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| First Time appeared |
Bouncycastle
Bouncycastle bc-csharp |
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| CPEs | cpe:2.3:a:bouncycastle:bc-csharp:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Bouncycastle
Bouncycastle bc-csharp |
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| Metrics |
cvssV3_1
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Sun, 04 Oct 2026 06:30:00 +0000
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| Metrics |
ssvc
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Fri, 02 Oct 2026 15:15:00 +0000
| Type | Values Removed | Values Added |
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| First Time appeared |
Legion Of The Bouncy Castle Inc.
Legion Of The Bouncy Castle Inc. bc-csharp |
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| Vendors & Products |
Legion Of The Bouncy Castle Inc.
Legion Of The Bouncy Castle Inc. bc-csharp |
Fri, 02 Oct 2026 07:15:00 +0000
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| Description | 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. | |
| Title | KCcmBlockCipher (DSTU 7624 CCM) tag not bound to nonce when no associated data is used | |
| Weaknesses | CWE-325 | |
| References |
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| Metrics |
cvssV4_0
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Status: PUBLISHED
Assigner: bcorg
Published: 2026-10-02T06:54:23.546Z
Updated: 2026-10-02T18:00:20.505Z
Reserved: 2026-07-16T23:53:32.558Z
Link: CVE-2026-16000
Updated: 2026-10-02T18:00:15.822Z
Status : Analyzed
Published: 2026-10-02T07:16:36.400
Modified: 2026-10-27T16:32:54.857
Link: CVE-2026-16000
No data.