Vulnerability Details 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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 1.0%
CVSS Severity
CVSS v3 Score 7.5
References
Products affected by CVE-2026-6331
-
cpe:2.3:a:wolfssl:wolfssl:3.15.5
-
cpe:2.3:a:wolfssl:wolfssl:3.15.6
-
cpe:2.3:a:wolfssl:wolfssl:3.15.7
-
cpe:2.3:a:wolfssl:wolfssl:3.15.8
-
cpe:2.3:a:wolfssl:wolfssl:4.0
-
cpe:2.3:a:wolfssl:wolfssl:4.0.0
-
cpe:2.3:a:wolfssl:wolfssl:4.1.0
-
cpe:2.3:a:wolfssl:wolfssl:4.2.0
-
cpe:2.3:a:wolfssl:wolfssl:4.2.0c
-
cpe:2.3:a:wolfssl:wolfssl:4.3.0
-
cpe:2.3:a:wolfssl:wolfssl:4.4.0
-
cpe:2.3:a:wolfssl:wolfssl:4.5.0
-
cpe:2.3:a:wolfssl:wolfssl:4.6.0
-
cpe:2.3:a:wolfssl:wolfssl:4.7.0
-
cpe:2.3:a:wolfssl:wolfssl:4.8.0
-
cpe:2.3:a:wolfssl:wolfssl:4.8.1
-
cpe:2.3:a:wolfssl:wolfssl:5.0.0
-
cpe:2.3:a:wolfssl:wolfssl:5.1.0
-
cpe:2.3:a:wolfssl:wolfssl:5.1.1
-
cpe:2.3:a:wolfssl:wolfssl:5.2.0
-
cpe:2.3:a:wolfssl:wolfssl:5.2.1
-
cpe:2.3:a:wolfssl:wolfssl:5.3.0
-
cpe:2.3:a:wolfssl:wolfssl:5.4.0
-
cpe:2.3:a:wolfssl:wolfssl:5.5.0
-
cpe:2.3:a:wolfssl:wolfssl:5.5.1
-
cpe:2.3:a:wolfssl:wolfssl:5.5.2
-
cpe:2.3:a:wolfssl:wolfssl:5.5.3
-
cpe:2.3:a:wolfssl:wolfssl:5.5.4
-
cpe:2.3:a:wolfssl:wolfssl:5.6.0
-
cpe:2.3:a:wolfssl:wolfssl:5.6.2
-
cpe:2.3:a:wolfssl:wolfssl:5.6.3
-
cpe:2.3:a:wolfssl:wolfssl:5.6.4
-
cpe:2.3:a:wolfssl:wolfssl:5.6.6
-
cpe:2.3:a:wolfssl:wolfssl:5.7.0
-
cpe:2.3:a:wolfssl:wolfssl:5.7.2
-
cpe:2.3:a:wolfssl:wolfssl:5.7.4
-
cpe:2.3:a:wolfssl:wolfssl:5.7.6
-
cpe:2.3:a:wolfssl:wolfssl:5.8.0
-
cpe:2.3:a:wolfssl:wolfssl:5.8.2
-
cpe:2.3:a:wolfssl:wolfssl:5.8.4