A vulnerability was found in mod_auth_mellon. An open redirect in the logout URL allows requests with backslashes to pass through by assuming that it is a relative URL, while the browsers silently convert backslash characters into forward slashes using treating them as an absolute URL. This mismatch allows an attacker to bypass the redirect URL validation logic in apr_uri_parse function.
Created mod_auth_mellon tracking bugs for this issue:
Affects: fedora-all [bug 1691771]
This issue has been addressed in the following products:
Red Hat Enterprise Linux 7
Via RHSA-2019:0766 https://access.redhat.com/errata/RHSA-2019:0766