CVE-2025-66614
Plain English Summary
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An attacker can bypass client certificate authentication in Apache Tomcat by sending different host names in the SNI extension and the HTTP host header, potentially gaining unauthorized access to resources. This vulnerability only affects configurations where client certificate authentication is enforced at the Connector level, not at the web application level, and it impacts specific versions of Tomcat.
Technical Description
Improper Input Validation vulnerability. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.14, from 10.1.0-M1 through 10.1.49, from 9.0.0-M1 through 9.0.112. The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.0 through 8.5.100. Older EOL versions are not affected. Tomcat did not validate that the host name provided via the SNI extension was the same as the host name provided in the HTTP host header field. If Tomcat was configured with more than one virtual host and the TLS configuration for one of those hosts did not require client certificate authentication but another one did, it was possible for a client to bypass the client certificate authentication by sending different host names in the SNI extension and the HTTP host header field. The vulnerability only applies if client certificate authentication is only enforced at the Connector. It does not apply if client certificate authentication is enforced at the web application. Users are recommended to upgrade to version 11.0.15 or later, 10.1.50 or later or 9.0.113 or later, which fix the issue.
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Published
Feb 17, 2026
about 2 months ago
Last Modified
Feb 18, 2026
about 2 months ago