CVE-2026-6331: low-severity vulnerability in wolfSSL
HMAC zero-length tag forgery in EVP_DigestVerifyFinal
Published · Updated
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8Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 2.1epss 0.2%
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:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Affected products
wolfSSL · wolfSSLRelated CVEs — wolfSSL
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