Adminer before 5.5.0 SSRF via PDO DSN Injection

Adminer before 5.5.0 contains a server-side request forgery vulnerability in the login form's server field validator, which only inspects leading integers for privileged ports and fails to reject non-numeric port values. Attackers can inject PDO DSN keys like host= and port= into the server parameter to bypass the privileged-port restriction and establish TCP connections to arbitrary internal hosts and ports before authentication.