phpBB 2.0.20 does not verify user-specified input variable types before being passed to type-dependent functions, which allows remote attackers to obtain sensitive information, as demonstrated by the (1) mode parameter to memberlist.php and the (2) highlight parameter to viewtopic.php that are used as an argument to the htmlspecialchars or urlencode functions, which displays the installation path in the resulting error message.

phpBB 2.0.20 does not properly verify user-specified input variables used as limits to SQL queries, which allows remote attackers to obtain sensitive information via a negative LIMIT specification, as demonstrated by the start parameter to memberlist.php, which reveals the SQL query in the resulting error message.

Unspecified vulnerability in phpBB before 2.0.22 has unknown impact and remote attack vectors related to "criteria for 'bad' redirection targets."

Certain forms in phpBB before 2.0.22 lack session checks, which has unknown impact and remote attack vectors.

Unspecified vulnerability in phpBB before 2.0.22 has unknown impact and remote attack vectors related to a "negative start parameter."

Cross-site scripting (XSS) vulnerability in the private message box implementation (privmsg.php) in phpBB 2.0.x allows remote authenticated users to inject arbitrary web script or HTML via the "Message body" field in a message to a non-existent user.

PHP remote file inclusion vulnerability in admin/admin_topic_action_logging.php in Admin Topic Action Logging Mod 0.95 and earlier, as used in phpBB 2.0 up to 2.0.21, allows remote attackers to execute arbitrary PHP code via a URL in the phpbb_root_path parameter.

usercp_avatar.php in PHPBB 2.0.20, when avatar uploading is enabled, allows remote attackers to use the server as a web proxy by submitting a URL to the avatarurl parameter, which is then used in an HTTP GET request.

PHP remote file inclusion vulnerability in template.php in phpBB 2 allows remote attackers to execute arbitrary PHP code via a URL in the page parameter. NOTE: followup posts have disputed this issue, stating that template.php does not appear in phpBB and does not use a $page variable. It is possible that this is a site-specific vulnerability, or an issue in a mod