The mail function in PHP 4.x to 4.2.2 does not filter ASCII control characters from its arguments, which could allow remote attackers to modify mail message content, including mail headers, and possibly use PHP as a "spam proxy."
move_uploaded_file in PHP does not does not check for the base directory (open_basedir), which could allow remote attackers to upload files to unintended locations on the system.
PHP 4.0.5 through 4.1.0 in safe mode does not properly cleanse the 5th parameter to the mail() function, which allows local users and possibly remote attackers to execute arbitrary commands via shell metacharacters.