CVE-2026-65637: Apache Tomcat improper input validation in incomplete fix

CVE-2026-65637 · Severity: critical · CVSS 9.8 · Published 2026-08-25

Apache Tomcat is a widely-used application server that hosts Java web applications. An improper input validation vulnerability stemming from an incomplete fix for a previous security issue could allow attackers to bypass protections and compromise the integrity or availability of hosted applications and services.

Technologies: Apache Tomcat, org.apache.tomcat:tomcat-coyote (Maven), org.apache.tomcat.embed:tomcat-embed-core (Maven). Vendors: Apache, Maven.

Quick answers

Is CVE-2026-65637 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-65637 being exploited in the wild.
How severe is CVE-2026-65637?
Critical severity, with a CVSS score of 9.8, published 25 August 2026.
Which products and versions are affected?
Apache Tomcat 11.0.20–11.0.24, 10.1.53–10.1.57, 9.0.115–9.0.120; org.apache.tomcat:tomcat-coyote (Maven) >= 11.0.20, < 11.0.25, ECOSYSTEM:introduced=11.0.20,fixed=11.0.25; org.apache.tomcat.embed:tomcat-embed-core (Maven) >= 11.0.20, < 11.0.25, ECOSYSTEM:introduced=11.0.20,fixed=11.0.25.
Is there a fix for CVE-2026-65637?
Yes. org.apache.tomcat:tomcat-coyote (Maven): upgrade to 11.0.25 or later; org.apache.tomcat.embed:tomcat-embed-core (Maven): upgrade to 11.0.25 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-65637 attacked?
It is attacked over the network, in a web application.
Am I affected by CVE-2026-65637?
Check whether you run Apache Tomcat, org.apache.tomcat:tomcat-coyote (Maven) or org.apache.tomcat.embed:tomcat-embed-core (Maven) 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.

How to fix

  • org.apache.tomcat:tomcat-coyote (Maven): upgrade to 11.0.25 or later
    # set org.apache.tomcat:tomcat-coyote to 11.0.25 in your pom.xml or build.gradle
  • org.apache.tomcat.embed:tomcat-embed-core (Maven): upgrade to 11.0.25 or later
    # set org.apache.tomcat.embed:tomcat-embed-core to 11.0.25 in your pom.xml or build.gradle

Technical details

This vulnerability is an improper input validation flaw in Apache Tomcat that arose from an incomplete fix to CVE-2026-32990. The issue affects Tomcat versions 11.0.20–11.0.24, 10.1.53–10.1.57, and 9.0.115–9.0.120. The vulnerability is exploitable via network attack without requiring authentication or special privileges. An attacker can leverage the insufficient input validation to bypass existing security controls and achieve unauthorized access or denial of service. Patches are available in versions 11.0.25, 10.1.58, and 9.0.121.

Affected products

  • Apache Tomcat 11.0.20–11.0.24, 10.1.53–10.1.57, 9.0.115–9.0.120

Identifiers

  • CVE-2026-65637
  • BIT-TOMCAT-2026-65637
  • GHSA-f525-44xv-f2qj

Timeline

  • 2026-08-25: disclosed

References

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