Cross-site request forgery (CSRF) vulnerability in system_firmware_restorefullbackup.php in the WebGUI in pfSense before 2.2.1 allows remote attackers to hijack the authentication of administrators for requests that delete arbitrary files via the deletefile parameter.
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.