KCcmBlockCipher (DSTU 7624 CCM) tag not bound to nonce when no associated data is used
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.
CVE-2026-16000
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-16000
bc-csharp
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://github.com/bcgit/bc-csharp",
"vendor": "Legion of the Bouncy Castle Inc.",
"product": "bc-csharp",
"versions": [
{
"status": "affected",
"version": "0",
"lessThan": "2.7.0",
"versionType": "semver"
}
],
"packageName": "BouncyCastle.Cryptography",
"programFiles": [
"crypto/src/crypto/modes/KCcmBlockCipher.cs"
],
"collectionURL": "https://www.nuget.org/packages/BouncyCastle.Cryptography",
"defaultStatus": "unaffected"
}
]- Related CVEs
- CVE-2026-16000
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #8106 · Revision 1
- Added to Heist Feed
- Publisher date