Several issues have been discovered in Apache module auth_mellon, which provides SAML 2.0 authentication. CVE-2019-3877 It was possible to bypass the redirect URL checking on logout, so the module could be used as an open redirect facility. CVE-2019-3878 When mod_auth_mellon is used in an Apache configuration which serves as a remote proxy with the http_proxy module, it was possible to bypass authentication by sending SAML ECP headers.