PHPIDS before 20070703 does not properly handle (1) arithmetic expressions and (2) unclosed comments, which allows remote attackers to inject arbitrary web script.
https://exchange.xforce.ibmcloud.com/vulnerabilities/35519
http://sla.ckers.org/forum/read.php?2%2C13209%2C13218
http://groups.google.com/group/php-ids/browse_thread/thread/3ec15f69d6b3dba0