Improper Verification of Cryptographic Signature in wolfSSL - CVE-2026-8720
Published: July 1, 2026
Vulnerability identifier: #VU136638
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-8720
CWE-ID: CWE-347
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: wolfSSL
Affected software:
wolfSSL
wolfSSL
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass MAC verification.
The vulnerability exists due to improper authentication in wc_Blake2bHmacFinal and wc_Blake2sHmacFinal when processing messages with keys longer than the block size. A remote attacker can use a key longer than the block size to bypass MAC verification.
This bug is specific to the HMAC-BLAKE2 APIs added in wolfSSL version 5.9.0.
How to mitigate CVE-2026-8720
Install security update from vendor's website.