In MODX Revolution before 2.5.7, an attacker might be able to trigger XSS by injecting a payload into the HTTP Host header of a request. This is exploitable only in conjunction with other issues such as Cache Poisoning.

In MODX Revolution before 2.5.7, a user with resource edit permissions can inject an XSS payload into the title of any post via the pagetitle parameter to connectors/index.php.

In MODX Revolution before 2.5.7, when PHP 5.3.3 is used, an attacker is able to include and execute arbitrary files on the web server due to insufficient validation of the action parameter to setup/index.php, aka directory traversal.

A stored web content injection vulnerability (WCI, a.k.a XSS) is present in MODX Revolution CMS version 2.5.6 and earlier. An authenticated user with permissions to edit users can save malicious JavaScript as a User Group name and potentially take control over victims' accounts. This can lead to an escalation of privileges providing complete administrative control over the CMS.