CVE-2026-6331 HMAC zero-length tag forgery in EVP_DigestVerifyFinal
LowCVSS 2.1
EPSS 0.19%
- Published
- Updated
- Exploit status
- No public exploit known
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.
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| wolfSSL | >= 3.15.5, <= 5.9.1 | No fix listed |
| debian/wolfssl(Debian:12) | < 5.5.4-2+deb12u3 | 5.5.4-2+deb12u3 |
| debian/wolfssl(Debian:12) | = 5.5.4-2 | No fix listed |
| debian/wolfssl(Debian:12) | = 5.5.4-2+deb12u1 | No fix listed |
| debian/wolfssl(Debian:12) | = 5.5.4-2+deb12u2 | No fix listed |
| debian/wolfssl(Debian:13) | < 5.7.2-0.1+deb13u2 | 5.7.2-0.1+deb13u2 |
| debian/wolfssl(Debian:13) | = 5.7.2-0.1 | No fix listed |
| debian/wolfssl(Debian:13) | = 5.7.2-0.1+deb13u1 | No fix listed |
| ubuntu/wolfssl(Ubuntu:22.04) | All versions | No fix listed |
| alpine/wolfssl(Alpine:v3.24) | >= 3.15.5, < 5.9.2-r0 | 5.9.2-r0 |
| ubuntu/wolfssl(Ubuntu:24.04) | All versions | No fix listed |
| ubuntu/wolfssl(Ubuntu:26.04) | All versions | No fix listed |
| ubuntu/wolfssl(Ubuntu:26.10) | All versions | No fix listed |
| wolfSSL | >= 3.15.5, < 5.9.2 | 5.9.2 |
| MariaDB Server(Azure Linux:3.0) | All versions | No fix listed |
References
- MSRC Security Update Guide vendor-advisory
- github.com issue-tracking patch
- www.wolfssl.com vendor-advisory
- Debian Security Tracker CVE-2026-6331 vendor-advisory
- Ubuntu CVE tracker vendor-advisory
- www.cve.org
- security.alpinelinux.org vendor-advisory
- bugs.debian.org issue-tracking