CVE-2026-6331
HMAC zero-length tag forgery in EVP_DigestVerifyFinal, where a zero-length tag could be accepted as valid during HMAC verification. In the OpenSSL-compatibility HMAC verify path the supplied signature length was only checked as not exceeding the MAC length, so a zero-length or otherwise truncated tag could pass verification. The fix requires the supplied tag length to exactly equal the MAC length and rejects a zero-length MAC, so a forged short or empty tag is no longer accepted.
- Score
- CVSS 3.1 7.5 High
- Status
- Analyzed - facts@wolfssl.com
- Published
- 2026-06-25
- Last modified
- 2026-06-26
- Weaknesses
- CWE-347
Affected products
References
- https://github.com/wolfSSL/wolfssl/pull/10192
- https://www.wolfssl.com/docs/security-vulnerabilities/
