What is CVE-2026-6331?

CVE-2026-6331 is a high-severity vulnerability in Wolfssl, classified under Improper Verification of Cryptographic Signature. CVSS score: 7.5/10. Published 2026-06-25.

How severe is CVE-2026-6331?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Wolfssl

CVE-2026-6331

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 exceedi…

EPSS: 0.001 (4.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

Affected products

Wolfssl — versions 3.15.5

Weakness classification (CWE)

CWE-347 — Improper Verification of Cryptographic Signature

References

facts@wolfssl.com (Patch, patch, Issue Tracking)
facts@wolfssl.com (Vendor Advisory)

Frequently asked questions

What is CVE-2026-6331?: CVE-2026-6331 is a high-severity vulnerability in Wolfssl, classified under Improper Verification of Cryptographic Signature. CVSS score: 7.5/10. Published 2026-06-25.
How severe is CVE-2026-6331?: High severity. CVSS v3 base score is 7.5 out of 10.