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

Source: https://junglewise.ai/threats/cve-2026-42498-apache-tomcat-authentication-header-exposure-in-websocket  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-12. Updated: 2026-05-18  
License: CC BY 4.0 with a link back

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](https://junglewise.ai/threats/technologies/tomcat), [org.apache.tomcat:tomcat (Maven)](https://junglewise.ai/threats/technologies/org-apache-tomcat-tomcat), [org.apache.tomcat:tomcat-catalina (Maven)](https://junglewise.ai/threats/technologies/org-apache-tomcat-tomcat-catalina), [org.apache.tomcat.embed:tomcat-embed-core (Maven)](https://junglewise.ai/threats/technologies/org-apache-tomcat-embed-tomcat-embed-core). Vendors: [Apache](https://junglewise.ai/threats/vendors/apache), [Maven](https://junglewise.ai/threats/vendors/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

  ```sh
  # 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

  ```sh
  # 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

  ```sh
  # 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

- [https://lists.apache.org/thread/n61zwf75jrv09rz90j4jssncm244bwdb](https://lists.apache.org/thread/n61zwf75jrv09rz90j4jssncm244bwdb)
- [http://www.openwall.com/lists/oss-security/2026/05/12/14](http://www.openwall.com/lists/oss-security/2026/05/12/14)
- [https://github.com/apache/tomcat/commit/169d725788ea6aec217ecac70fe4161c837ba423](https://github.com/apache/tomcat/commit/169d725788ea6aec217ecac70fe4161c837ba423)
- [https://github.com/apache/tomcat/commit/6cbe274592ef2d11607b5b188e1df649de52f8d5](https://github.com/apache/tomcat/commit/6cbe274592ef2d11607b5b188e1df649de52f8d5)
- [https://github.com/apache/tomcat/commit/b7b173694d588ddcfa432f079baf763cbbbaa5c4](https://github.com/apache/tomcat/commit/b7b173694d588ddcfa432f079baf763cbbbaa5c4)

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