FileRun before 2026.3.0 contains a PHP object injection vulnerability that allows authenticated attackers to execute arbitrary code by exploiting incorrect options passed to unserialize() in the Perms::getPerms() method, where a positional array is used instead of the required named-key array to disable class instantiation. Attackers with database write access can inject a serialized gadget chain into the permissions table columns processed on every authenticated page load to write arbitrary files, such as PHP webshells, to web-accessible paths.