mod_auth_openidc is an OpenID Certified™ authentication and authorization module for the Apache 2.x HTTP server. Versions prior to 2.4.12.2 are vulnerable to Open Redirect. When providing a logout parameter to the redirect URI, the existing code in oidc_validate_redirect_url() does not properly check for URLs that start with /\t, leading to an open redirect. This issue has been patched in version 2.4.12.2. Users unable to upgrade can mitigate the issue by configuring mod_auth_openidc to only allow redirection when the destination matches a given regular expression with OIDCRedirectURLsAllowed.
https://lists.debian.org/debian-lts-announce/2023/07/msg00020.html
https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-q6f2-285m-gr53
https://github.com/zmartzone/mod_auth_openidc/blob/v2.4.12.1/auth_openidc.conf#L975-L984