Vulnerability Details CVE-2026-8720
wc_Blake2bHmacFinal and wc_Blake2sHmacFinal discard the message when the key length exceeds the block size, producing a MAC that is independent of the input. When the supplied key is longer than the BLAKE2 block size the key-hashing branch reinitialized the running hash state, discarding the accumulated message data, so the resulting MAC depended only on the key and not on the message being authenticated. This bug is specific to the HMAC-BLAKE2 APIs that were added in wolfSSL version 5.9.0.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 0.7%
CVSS Severity
CVSS v3 Score 7.5
References