CVE-2026-55276: Apache Tomcat incorrect control flow in web.xml logging

CVE-2026-55276 · Severity: critical · CVSS 9.1 · Published 2026-06-29

Apache Tomcat, a widely used web server for Java applications, contains a logging flaw where certain security configurations are omitted from diagnostic logs. Specifically, when the server logs its effective configuration, it fails to include special user roles and empty authorization constraints. While this does not directly allow an attacker to break into the system, it can mislead administrators during security audits or troubleshooting, potentially hiding the true security posture of the application.

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

Quick answers

Is CVE-2026-55276 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-55276 being exploited in the wild.
How severe is CVE-2026-55276?
Critical severity, with a CVSS score of 9.1, published 29 June 2026.
Which products and versions are affected?
org.apache.tomcat:tomcat (Maven) >= 11.0.0-M1, < 11.0.23, ECOSYSTEM:introduced=11.0.0-M1,fixed=11.0.23; org.apache.tomcat:tomcat-util-scan (Maven) >= 11.0.0-M1, < 11.0.23, ECOSYSTEM:introduced=11.0.0-M1,fixed=11.0.23; org.apache.tomcat.embed:tomcat-embed-core (Maven) >= 11.0.0-M1, < 11.0.23, ECOSYSTEM:introduced=11.0.0-M1,fixed=11.0.23.
Is there a fix for CVE-2026-55276?
Yes. org.apache.tomcat:tomcat (Maven): upgrade to 11.0.23 or later; org.apache.tomcat:tomcat-util-scan (Maven): upgrade to 11.0.23 or later; org.apache.tomcat.embed:tomcat-embed-core (Maven): upgrade to 11.0.23 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-55276 attacked?
It is attacked with local access, in a software library.
Am I affected by CVE-2026-55276?
Check whether you run org.apache.tomcat:tomcat (Maven), org.apache.tomcat:tomcat-util-scan (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 (Maven): upgrade to 11.0.23 or later
    # set org.apache.tomcat:tomcat to 11.0.23 in your pom.xml or build.gradle
  • org.apache.tomcat:tomcat-util-scan (Maven): upgrade to 11.0.23 or later
    # set org.apache.tomcat:tomcat-util-scan to 11.0.23 in your pom.xml or build.gradle
  • org.apache.tomcat.embed:tomcat-embed-core (Maven): upgrade to 11.0.23 or later
    # set org.apache.tomcat.embed:tomcat-embed-core to 11.0.23 in your pom.xml or build.gradle

Technical details

An 'Always-Incorrect Control Flow Implementation' (CWE-670) exists in Apache Tomcat's configuration logging mechanism. When the server generates a log of the effective web.xml (the merged configuration used at runtime), it fails to include specific security elements, namely special roles and empty authorization constraints. This is a diagnostic/logging integrity issue rather than a direct bypass of runtime enforcement. An attacker cannot trigger this to gain unauthorized access, but it impacts the ability of security engineers to verify the active security constraints via logs. The issue is resolved in versions 11.0.23, 10.1.56, and 9.0.119.

Affected products

  • Apache Tomcat 11.0.0-M1 to 11.0.22, 10.1.0-M1 to 10.1.55, 9.0.0.M1 to 9.0.118, 8.5.0 to 8.5.100

Identifiers

  • CVE-2026-55276
  • BIT-TOMCAT-2026-55276
  • GHSA-mqg3-r7h5-24x4

Timeline

  • 2026-06-29: disclosed
  • 2026-06-29: advisory

References

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