CVE-2025-15346 PUBLISHED

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

Assigner: wolfSSL
Reserved: 29.12.2025 Published: 07.01.2026 Updated: 08.01.2026

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.

Metrics

CVSS 4.0

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/AU:Y
CVSS Score: 9.3

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	High	Confidentiality	None
Attack Complexity	Low	Integrity	High	Integrity	None
Attack Requirements	None	Availability	None	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

Product Status

Vendor	wolfSSL
Product	wolfSSL-py
Versions	Default: unaffected affected from 5.3.0 to 5.8.2 (incl.)

Credits

Matan Radomski finder

References

Problem Types

CWE-306 Missing Authentication for Critical Function CWE
CWE-287 Improper Authentication CWE

Impacts

CAPEC-115 Authentication Bypass
CAPEC-220 Client-Server Protocol Manipulation