[SECURITY] CVE-2026-65637 Apache Tomcat - HTTP/2 no-authority bypass of strict SNI validation

CVE-2026-65637 Apache Tomcat - HTTP/2 no-authority bypass of strict SNI 
validation

Severity: Moderate

Vendor: The Apache Software Foundation

Versions Affected:
Apache Tomcat 11.0.20 to 11.0.24
Apache Tomcat 10.1.53 to 10.1.57
Apache Tomcat 9.0.115 to 9.0.120

Description:
The fix for CVE-2026-32990 was incomplete.

Mitigation:
Users of the affected versions should apply one of the following
mitigations:
- Remove the examples web application
- Upgrade to Apache Tomcat 11.0.25
- Upgrade to Apache Tomcat 10.1.59
- Upgrade to Apache Tomcat 9.0.121

Note: This issue was fixed in Apache Tomcat 10.1.58 but the release vote 
for the 10.1.58 release candidate did not pass. Therefore, although 
users must download 10.1.59 to obtain a version that includes a fix for 
this issue, version 10.1.58 is not included in the list of affected 
versions.

Credit:
This issue was identified by:
- Parag Ambildhuke (https://github.com/paragxa)

History:
2026-08-25 Original advisory

References:
[1] https://tomcat.apache.org/security-11.html
[2] https://tomcat.apache.org/security-10.html
[3] https://tomcat.apache.org/security-9.html