A flaw was found in mod_auth_openidc before version 2.4.0.1. An open redirect issue exists in URLs with trailing slashes similar to CVE-2019-3877 in mod_auth_mellon.
https://lists.debian.org/debian-lts-announce/2020/07/msg00028.html
https://groups.google.com/forum/#%21topic/mod_auth_openidc/boy1Ba3Gdk4
https://github.com/zmartzone/mod_auth_openidc/pull/451
https://github.com/zmartzone/mod_auth_openidc/commit/ce37080c6aea30aabae8b4a9b4eea7808445cc8e
https://github.com/zmartzone/mod_auth_openidc/commit/5c15dfb08106c2451c2c44ce7ace6813c216ba75