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.
Does this matter?
Lower severity and a low EPSS score (0.16%). Track it; it rarely justifies an emergency change on its own.
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 4.0
- 5.9 MEDIUMCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.16% probability · 5th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-354
- Affected
- wolfssl/wolfssl
- Source
- facts@wolfssl.com
References
- https://github.com/wolfSSL/wolfssl/pull/10447Issue Tracking, Patch
- https://www.wolfssl.com/docs/security-vulnerabilities/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.