A crafted method sent through HTTP/2 will bypass validation and be forwarded by mod_proxy, which can lead to request splitting or cache poisoning. This issue affects Apache HTTP Server 2.4.17 to 2.4.48.
https://www.tenable.com/security/tns-2021-17
https://www.oracle.com/security-alerts/cpujan2022.html
https://www.oracle.com/security-alerts/cpuapr2022.html
https://security.netapp.com/advisory/ntap-20210917-0004/
https://security.gentoo.org/glsa/202208-20
https://portswigger.net/research/http2
https://lists.debian.org/debian-lts-announce/2023/03/msg00002.html
https://github.com/apache/httpd/commit/ecebcc035ccd8d0e2984fe41420d9e944f456b3c.patch