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."

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

PHP remote file inclusion vulnerability in admin/admintopicactionlogging.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 phpbbrootpath 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.

Cross-site request forgery (CSRF) vulnerability in phpBB 2.0.21 allows remote authenticated users to send unauthorized messages as an arbitrary user via unspecified vectors. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information.

phpBB 2.0.21 does not properly handle pathnames ending in %00, which allows remote authenticated administrative users to upload arbitrary files, as demonstrated by a query to admin/adminboard.php with an avatarpath parameter ending in .php%00.