PT-2026-52604 · Wolfssl · Wolfssl

Nicholas Carlini · Published 2026-06-25 · Updated 2026-06-25 · CVE-2026-6331

NVD

CVSS v4.0

2.1

Low

Base vector

AV:L/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

HMAC zero-length tag forgery in EVP DigestVerifyFinal, where a zero-length tag could be accepted as valid during HMAC verification. In the OpenSSL-compatibility HMAC verify path the supplied signature length was only checked as not exceeding the MAC length, so a zero-length or otherwise truncated tag could pass verification. The fix requires the supplied tag length to exactly equal the MAC length and rejects a zero-length MAC, so a forged short or empty tag is no longer accepted.

Fix

Improper Verification of Cryptographic Signature

Weakness Enumeration

CWE-347

Related Identifiers

CVE-2026-6331

Affected Products

Wolfssl

References · 3

• https://nvd.nist.gov/vuln/detail/CVE-2026-6331 · Security Note
• https://github.com/wolfSSL/wolfssl/pull/10192 · Patch
• https://wolfssl.com/docs/security-vulnerabilities · Note