If Apache Tomcat 8.5.0 to 8.5.82, 9.0.0-M1 to 9.0.67, 10.0.0-M1 to 10.0.26 or 10.1.0-M1 to 10.1.0 was configured to ignore invalid HTTP headers via setting rejectIllegalHeader to false (the default for 8.5.x only), 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.
github.com/apache/tomcat
github.com/apache/tomcat/commit/0d089a15047faf9cb3c82f80f4d28febd4798920
github.com/apache/tomcat/commit/4c7f4fd09d2cc1692112ef70b8ee23a7a037ae77
github.com/apache/tomcat/commit/a1c07906d8dcaf7957e5cc97f5cdbac7d18a205a
github.com/apache/tomcat/commit/c9fe754e5d17e262dfbd3eab2a03ca96ff372dc3
lists.apache.org/thread/zzcxzvqfdqn515zfs3dxb7n8gty589sq
nvd.nist.gov/vuln/detail/CVE-2022-42252
security.gentoo.org/glsa/202305-37
tomcat.apache.org/security-10.html
tomcat.apache.org/security-8.html
tomcat.apache.org/security-9.html