CVE-2025-15346 wolfSSL Python library `CERT_REQUIRED` mode fails to enforce client certificate requirement
Attackers can bypass mutual TLS authentication by omitting client certificates when CERT_REQUIRED is configured, allowing unauthorized access.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-15346?
CVE-2025-15346 is a critical authentication bypass vulnerability in wolfSSL-py, published on 7 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2025-15346?
3 open source packages ship an affected version, including wolfssl.
| Package | Affected | Fixed in |
|---|---|---|
wolfssl PyPI | All versions | 5.8.4.post0 |
wolfssl PyPI | All versions | 5.8.4.post0 |
wolfssl PyPI | All versions | 5.8.4.post0 |
How do I fix CVE-2025-15346?
Upgrade wolfssl to 5.8.4.post0 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2025-15346 being exploited?
There is no known exploitation of CVE-2025-15346 in the wild and no public exploit code.
Sources
Also known as GHSA-vj87-jj27-4h9c, PYSEC-2026-575.