wolfSSL Python module vulnerable to Improper Authentication

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

9.3 · 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 · score source

EPSS

• CVE-2025-15346: 0.33% estimated exploitation activity in the next 30 days; percentile 26.85 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

A vulnerability in the handling of verifymode = CERTREQUIRED in the wolfssl Python package (wolfssl-py) causes client certificate requirements to not be fully enforced. Because the WOLFSSLVERIFYFAILIFNOPEERCERT flag was not included, the behavior effectively matched CERTOPTIONAL: 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.

Published by the source

8 Jan 2026, 00:31 UTC

Last modified by the source

29 Jun 2026, 12:26 UTC

Source last checked

26 Oct 2026, 13:36 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-vj87-jj27-4h9c

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-vj87-jj27-4h9c

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# Patch Next advisory brief: CVE-2025-15346

Advisory: wolfSSL Python module vulnerable to Improper Authentication
IDs: CVE-2025-15346, GHSA-vj87-jj27-4h9c
Record: https://patchnext.com/advisories/cve-2025-15346 (revision 3, source checked 26 Oct 2026, 13:36 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: wolfssl 5.8.4.post0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI wolfssl: affected < 5.8.4.post0; fixed in 5.8.4.post0

## Suggested inspection (read-only)
- `python -m pip show wolfssl`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on wolfssl.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-vj87-jj27-4h9c (OSV record GHSA-vj87-jj27-4h9c lists affected ranges: PyPI wolfssl >=0 <5.8.4.post0 (fixed))
- Verified: https://github.com/advisories/GHSA-vj87-jj27-4h9c (GitHub-reviewed advisory GHSA-vj87-jj27-4h9c lists affected ranges: PyPI wolfssl >=0 <5.8.4.post0)

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