CVE-2026-42498: Apache Tomcat authentication header exposure in WebSocket authentication

CVE-2026-42498 · Severity: high · CVSS 7.3 · Published 2026-05-12

Apache Tomcat is a widely used web server and application container. A vulnerability in its WebSocket client could cause sensitive login credentials (authentication headers) to be sent to the wrong server if a connection is redirected. This could allow an attacker to intercept credentials and gain unauthorized access to protected systems or data.

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

Quick answers

Is CVE-2026-42498 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-42498 being exploited in the wild.
How severe is CVE-2026-42498?
High severity, with a CVSS score of 7.3, published 12 May 2026.
Which products and versions are affected?
Apache Tomcat 11.0.0-M1 through 11.0.21, 10.1.0-M1 through 10.1.54, 9.0.2 through 9.0.117, 8.5.24 through 8.5.100, 7.0.83 through 7.0.109; org.apache.tomcat:tomcat (Maven) ECOSYSTEM:introduced=0,fixed=9.0.118; org.apache.tomcat:tomcat-catalina (Maven) ECOSYSTEM:introduced=0,fixed=9.0.118; org.apache.tomcat.embed:tomcat-embed-core (Maven) ECOSYSTEM:introduced=0,fixed=9.0.118.
Is there a fix for CVE-2026-42498?
Yes. org.apache.tomcat:tomcat (Maven): upgrade to 9.0.118 or later; org.apache.tomcat:tomcat-catalina (Maven): upgrade to 9.0.118 or later; org.apache.tomcat.embed:tomcat-embed-core (Maven): upgrade to 9.0.118 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-42498 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-42498?
Check whether you run Apache Tomcat, org.apache.tomcat:tomcat (Maven), org.apache.tomcat:tomcat-catalina (Maven) or one of the others listed 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 9.0.118 or later
    # set org.apache.tomcat:tomcat to 9.0.118 in your pom.xml or build.gradle
  • org.apache.tomcat:tomcat-catalina (Maven): upgrade to 9.0.118 or later
    # set org.apache.tomcat:tomcat-catalina to 9.0.118 in your pom.xml or build.gradle
  • org.apache.tomcat.embed:tomcat-embed-core (Maven): upgrade to 9.0.118 or later
    # set org.apache.tomcat.embed:tomcat-embed-core to 9.0.118 in your pom.xml or build.gradle

Technical details

A vulnerability exists in the Apache Tomcat WebSocket client where it fails to properly clear or validate the destination of authentication headers during a redirect. If a WebSocket connection request is redirected after the initial authentication step, the client presents the most recent 'Authorization' header to the new target host. This is a classic information exposure issue (CWE-200) where sensitive credentials intended for one host are leaked to another. The vulnerability can be exploited by a network-based attacker who can trigger or influence a redirect to a malicious host. Patches have been released for all major supported branches (9.0.118, 10.1.55, 11.0.22).

Affected products

  • Apache Tomcat 11.0.0-M1 to 11.0.21, 10.1.0-M1 to 10.1.54, 9.0.2 to 9.0.117, 8.5.24 to 8.5.100, 7.0.83 to 7.0.109

Identifiers

  • CVE-2026-42498
  • GHSA-fv25-8xcx-gqjc

Timeline

  • 2026-05-12: disclosed
  • 2026-05-12: advisory

References

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