CVE-2025-66614
tomcat: Client certificate verification bypass due to virtual host mapping
Severity
ModerateRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · February 18, 2026
Updated · September 28, 2026
Description
A certificate validation flaw has been found in Apache Tomcat. omcat 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.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
CVSS / CWE
CVSS 3.1 · 5.3CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
CWE-1289 · Improper Validation of Unsafe Equivalence in Input