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Critical · 9.3 CVE-2025-15346 EUVD-2026-1463GHSA-vj87-jj27-4h9cPYSEC-2026-575

wolfSSL Python library `CERT_REQUIRED` mode fails to enforce client certificate requirement

Published Jan 7, 2026 · Updated Jan 8, 2026 · Assigned by wolfSSL

Description

A vulnerability in the handling of verify_mode = CERT_REQUIRED in the wolfssl Python package (wolfssl-py) causes client certificate requirements to not be fully enforced. 

Because the WOLFSSL_VERIFY_FAIL_IF_NO_PEER_CERT flag was not included, the behavior effectively matched CERT_OPTIONAL: a peer certificate was verified if presented, but connections were incorrectly authenticated when no client certificate was provided. 

This results in improper authentication, allowing attackers to bypass mutual TLS (mTLS) client authentication by omitting a client certificate during the TLS handshake. 

The issue affects versions up to and including 5.8.2.

Affected products

VendorProductAffectedFixed
wolfSSL wolfSSL-py 5.3.0 – ≤ 5.8.2 —

Affected packages

EcosystemPackageAffectedFixedRecord
PyPI wolfssl < 5.8.4.post0 5.8.4.post0 GHSA-vj87-jj27-4h9c

References