What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-12 · updated 2026-10-26
• Weakness: CWE-200

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.

Affected products

• Apache Tomcat: from 7.0.0 through 7.0.109; from 8.5.0 through 8.5.100; from 9.0.0 before 9.0.118; from 10.1.0 before 10.1.55; from 11.0.0 before 11.0.22 — fixed in 9.0.118, 10.1.55, 11.0.22

How to fix

Upgrade to a fixed version: Apache Tomcat 9.0.118, 10.1.55, 11.0.22. Check the vendor advisory for mitigations.

References

• https://lists.apache.org/thread/n61zwf75jrv09rz90j4jssncm244bwdb
• http://www.openwall.com/lists/oss-security/2026/05/12/14

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