mod_auth_openidc is an authentication/authorization module for the Apache 2.x HTTP server that functions as an OpenID Connect Relying Party, authenticating users against an OpenID Connect Provider. In versions prior to 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the target_link_uri parameter. A patch in version 2.4.9.4 made it so that the OIDCRedirectURLsAllowed setting must be applied to the target_link_uri parameter. There are no known workarounds aside from upgrading to a patched version.
Exploitability
AV:NAC:LPR:NUI:RScope
S:CImpact
C:NI:LA:N4.7/CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:NInput Validation