https://bugzilla.redhat.com/show_bug.cgi?id=1038555 It was found that in pam_userdb module for Pam, password hashes weren't compared case-sensitively, which could lead to acceptance of hashes for completely different passwords, which shouldn't be accepted. After hashing the user's password with crypt(), pam_userdb compares the result to the stored hash case-insensitively with strncasecmp(), which should be avoided, as it could result in an increased possibility of a successful brute-force attack.