CVE-2026-86243: Apache Tomcat Native: DoS via TLS handshake

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-23 · updated 2026-10-06
Weakness: CWE-126

Description

Buffer over-read vulnerability in Apache Tomcat Native during the TLS handshake permits a malicious user to trigger a DoS via a JVM crash. This issue affects Apache Tomcat Native: from 2.0.0 through 2.0.15, from 1.3.0 through 1.3.8. Earlier, unsupported versions may also be affected. Users are recommended to upgrade to version 1.3.9 or 2.0.16, which fix the issue.

Affected products

Apache Software Foundation Apache Tomcat Native: from 1.3.0 before 1.3.9; from 2.0.0 before 2.0.16 — fixed in 1.3.9, 2.0.16

How to fix

Upgrade to a fixed version: Apache Software Foundation Apache Tomcat Native 1.3.9, 2.0.16. Check the vendor advisory for mitigations.

References

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