PHP remote file inclusion vulnerability in top/list.php in phpBB TopList 1.3.8 and earlier allows remote attackers to include arbitrary files via the returnpath parameter.
phpBB 2.0.11, and possibly other versions, with remote avatars and avatar uploading enabled, allows local users to read arbitrary files by providing both a local and remote location for an avatar, then modifying the "Upload Avatar from a URL:" field to reference the target file.