viewtopic.php in phpBB 2.x before 2.0.11 improperly URL decodes the highlight parameter when extracting words and phrases to highlight, which allows remote attackers to execute arbitrary PHP code by double-encoding the highlight value so that special characters are inserted into the result, which is then processed by PHP exec, as exploited by the Santy.A worm.

PHP remote file inclusion vulnerability in /includes/kbconstants.php in Knowledge Base Mod for PHPbb 2.0.2 and earlier allows remote attackers to execute arbitrary PHP code via a URL in the modulerootpath parameter.

calendarscheduler.php in Topic Calendar 1.0.1 module for phpBB, when running on a Microsoft IIS server, allows remote attackers to obtain sensitive information via invalid parameters, which reveal the path in an error message.

Cross-site scripting (XSS) vulnerability in calendarscheduler.php in the Topic Calendar 1.0.1 module for phpBB allows remote attackers to inject arbitrary web script or HTML via the start parameter.