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.

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

The gen_rand_string function in phpBB 2.0.19 uses insufficiently random data (small value space) to create the activation key ("validation ID") that is sent by e-mail when establishing a password, which makes it easier for remote attackers to obtain the key and modify passwords for existing accounts or create new accounts.

Cross-site request forgery (CSRF) vulnerability in phpBB 2.0.19, when Link to off-site Avatar or bbcode (IMG) are enabled, allows remote attackers to perform unauthorized actions as a logged in user via a link or IMG tag in a user profile, as demonstrated using links to (1) admin/admin_users.php and (2) modcp.php.

Cross-site scripting (XSS) vulnerability in admin_smilies.php in phpBB 2.0.19 allows remote attackers to inject arbitrary web script or HTML via Javascript events such as "onmouseover" in the (1) smile_url or (2) smile_emotion parameters, which bypasses a check for "<" and ">" characters.

phpBB 2.0.19 and earlier allows remote attackers to cause a denial of service (application crash) by (1) registering many users through profile.php or (2) using search.php to search in a certain way that confuses the database.

SQL injection vulnerability in phpBB 2 before 2.0.18 allows remote attackers to execute arbitrary SQL commands via the topic type.

A "missing request validation" error in phpBB 2 before 2.0.18 allows remote attackers to edit private messages of other users, probably by modifying certain parameters or other inputs.

phpBB 2.0.17 and earlier, when the register_long_arrays directive is disabled, allows remote attackers to modify global variables and bypass security mechanisms because PHP does not define the associated HTTP_* variables.