CVE-2025-15346

Critical

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.

SeverityCritical

CVSS9.3

Exploit probability—

ProductWolfssl

PublishedJan 8, 2026

First seenJan 8, 2026

Weakness typeCWE-306Missing authentication for critical function CWE-287Improper authentication

How to fix

Update

wolfssl5.8.4.post0 or later

Affected products

Product	Affected versions	Fixed in
wolfsslPyPI	v < 5.8.4.post0	5.8.4.post0

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