Vulnerability Description
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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Wolfssl | Wolfssl | >= 5.9.0, < 5.9.2 |
Related Weaknesses (CWE)
References
- https://github.com/wolfSSL/wolfssl/pull/10447Issue TrackingPatch
- https://www.wolfssl.com/docs/security-vulnerabilities/Vendor Advisory
FAQ
What is CVE-2026-8720?
CVE-2026-8720 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 B...
How severe is CVE-2026-8720?
CVE-2026-8720 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-8720?
Check the references section above for vendor advisories and patch information. Affected products include: Wolfssl Wolfssl.