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.
Published: 2026-02-17Modified: 2026-03-11
CVSS 3.xCRITICAL 9.1
CVSS:3.x/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N