Quick answers
- Is CVE-2026-78437 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-78437 being exploited in the wild.
- How severe is CVE-2026-78437?
- High severity, with a CVSS score of 7.3, published 23 September 2026.
- Which products and versions are affected?
- Apache Tomcat 11.0.19 through 11.0.25, 10.1.53 through 10.1.59, 9.0.116 through 9.0.121.
- Is there a fix for CVE-2026-78437?
- A patch was published on 2026-09-23: Fixes available in versions 11.0.26, 10.1.60, 9.0.122 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-78437 attacked?
- It is attacked over the network, in a web application.
- Am I affected by CVE-2026-78437?
- Check whether you run Apache Tomcat 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
An incomplete cleanup vulnerability in Tomcat's HTTP/2 request handling allows a malformed request to leave resources in an inconsistent state, which can cause subsequent requests from other users to fail depending on timing. The vulnerability is triggered via network-based HTTP/2 requests and requires no authentication or user interaction. An attacker can disrupt availability for other users without gaining direct access to their data.
Affected products
- Apache Tomcat 11.0.19 through 11.0.25, 10.1.53 through 10.1.59, 9.0.116 through 9.0.121
Timeline
- 2026-09-23: disclosed
- 2026-09-23: patched: Fixes available in versions 11.0.26, 10.1.60, 9.0.122