The "OpenID Connect Relying Party and OAuth 2.0 Resource Server" (aka mod_auth_openidc) module before 2.1.5 for the Apache HTTP Server does not skip OIDC_CLAIM_ and OIDCAuthNHeader headers in an "OIDCUnAuthAction pass" configuration, which allows remote attackers to bypass authentication via crafted HTTP traffic.
https://github.com/pingidentity/mod_auth_openidc/releases/tag/v2.1.5
https://github.com/pingidentity/mod_auth_openidc/issues/222
https://github.com/pingidentity/mod_auth_openidc/blob/master/ChangeLog