# CVE-2026-86247: Apache Tomcat Native race condition in client certificate verification

Source: https://junglewise.ai/threats/cve-2026-86247-race-condition-within-a-thread-vulnerability-in-apache-tomcat  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-23. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-86247 · Severity: high · CVSS 7.4 · Published 2026-09-23

Apache Tomcat Native is a library that provides native bindings for Tomcat web servers, including SSL/TLS certificate handling. A race condition in certificate verification logic allows attackers to bypass client certificate requirements in certain configurations, potentially granting unauthorized access to applications that rely on certificate-based authentication.

Technologies: [Apache Tomcat Native](https://junglewise.ai/threats/technologies/apache-tomcat-native). Vendors: [Apache](https://junglewise.ai/threats/vendors/apache).

## Quick answers

**Is CVE-2026-86247 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-86247 being exploited in the wild.

**How severe is CVE-2026-86247?** High severity, with a CVSS score of 7.4, published 23 September 2026.

**Which products and versions are affected?** Apache Tomcat Native 2.0.0 through 2.0.15, 1.3.0 through 1.3.8.

**Is there a fix for CVE-2026-86247?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-86247 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-86247?** Check whether you run Apache Tomcat Native at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A race condition within a thread in Apache Tomcat Native allows client certificate verification requirements to be down-graded for some configurations. The vulnerability exists in versions 2.0.0-2.0.15 and 1.3.0-1.3.8. An attacker on the network can exploit this condition to bypass client certificate authentication protections; no user interaction or prior authentication is required.

## Affected products

- Apache Tomcat Native 2.0.0 through 2.0.15, 1.3.0 through 1.3.8

## Timeline

- 2026-09-23: disclosed

## References

- [https://lists.apache.org/thread/obsson6zhvfg0wsp2bx602l61ltj87r1](https://lists.apache.org/thread/obsson6zhvfg0wsp2bx602l61ltj87r1)
- [http://www.openwall.com/lists/oss-security/2026/09/23/33](http://www.openwall.com/lists/oss-security/2026/09/23/33)

## Related threats

- [Apache Tomcat Native insecure default OpenSSL options](https://junglewise.ai/threats/cve-2026-86246-initialization-of-a-resource-with-an-insecure-default)
- [Apache Tomcat Native buffer over-read in TLS handshake](https://junglewise.ai/threats/cve-2026-86243-buffer-over-read-vulnerability-in-apache-tomcat-native-during-the)
- [Apache Tomcat improper authentication in CLIENT_CERT validation](https://junglewise.ai/threats/cve-2026-29145-apache-tomcat-improper-authentication-in-client-cert-validation)