CVE-2026-8720
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk2th percentile — higher than 2% of all known CVEs
Summary
The wc_Blake2bHmacFinal and wc_Blake2sHmacFinal functions in the wolfSSL library have an issue when the key length exceeds the block size, resulting in a MAC that is independent of the input data. When a key is too long, the hashing state is reset, causing the loss of message data.
Risk Assessment
Organizations may be vulnerable to authentication fraud as the generated MAC does not reflect the actual message data. This could lead to unauthorized access or data manipulation.
Recommendation
It is recommended to update to the latest version of wolfSSL to mitigate this vulnerability and to monitor the use of HMAC-BLAKE2 in applications.
Original NVD description (English source)
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.