Fixed in Apache Tomcat 9.0.68

Low: Apache Tomcat request smuggling CVE-2022-42252

If Tomcat was configured to ignore invalid HTTP headers via setting rejectIllegalHeader to false (not the default), Tomcat did not reject a request containing an invalid Content-Length header making a request smuggling attack possible if Tomcat was located behind a reverse proxy that also failed to reject the request with the invalid header.

This was fixed with commit 4c7f4fd0.

This issue was reported to the Apache Tomcat Security team on 29 September 2022. The issue was made public on 31 October 2022.

Affects: 9.0.0-M1 to 9.0.67