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CVE-2026-15999

AES-CCM decryption accepts zero or out-of-range tag length, bypassing authentication PUBLISHED

Description (CNA)

Improper validation of integrity check value in the AES-CCM implementation (CcmParameters and CcmBlockCipher) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an on-path attacker to modify CCM-encrypted content without detection via an AlgorithmIdentifier whose CCMParameters declare an authentication tag (aes-ICVlen) of zero or another length outside the RFC 5084 set, because CcmParameters accepted any value and CcmBlockCipher validated the tag length only when encrypting, so decryption compared a zero-length or very short tag. Affected paths include ParameterUtilities.GetCipherParameters, used by CmsEnvelopedData and CmsEnvelopedDataParser for EnvelopedData encrypted with AES-CCM, and any caller passing an unchecked tag length to CcmBlockCipher for decryption.

Affected (CNA)

Vendor / productVersions
Legion of the Bouncy Castle Inc. / bc-csharpaffected 0 before 2.7.0

CWE

CWE-354

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.