The messageoptions function in includes/ucp/ucppmoptions.php in phpBB before 3.0.13 does not properly validate the form key, which allows remote attackers to conduct CSRF attacks and change the full folder setting via unspecified vectors.
Cross-site scripting (XSS) vulnerability in includes/startup.php in phpBB before 3.0.13 allows remote attackers to inject arbitrary web script or HTML via vectors related to "Relative Path Overwrite."