Vulnerability Description
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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Wolfssl | Wolfssl | >= 3.15.5, < 5.9.2 |
Related Weaknesses (CWE)
References
- https://github.com/wolfSSL/wolfssl/pull/10192Issue TrackingPatch
- https://www.wolfssl.com/docs/security-vulnerabilities/Vendor Advisory
FAQ
What is CVE-2026-6331?
CVE-2026-6331 is a vulnerability with a CVSS score of 7.5 (HIGH). 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...
How severe is CVE-2026-6331?
CVE-2026-6331 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-6331?
Check the references section above for vendor advisories and patch information. Affected products include: Wolfssl Wolfssl.