Pedro Lineu Orso chetcpasswd before 2.4 relies on the X-Forwarded-For HTTP header when verifying a client's status on an IP address ACL, which allows remote attackers to gain unauthorized access by spoofing this header.

Pedro Lineu Orso chetcpasswd 2.3.3 provides a different error message when a request with a valid username fails, compared to a request with an invalid username, which allows remote attackers to determine valid usernames on the system.