Software Engineering Institute

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Fortinet FortiOS 5.0.5, and possibly earlier versions, contains a cross-site scripting vulnerability. The "mkey" parameter in the "/firewall/schedule/recurrdlg" page is vulnerable to a reflected cross-site scripting attack.

A remote unauthenticated attacker may be able to execute arbitrary script in the context of the end-user's browser session.

Apply an Update

The vendor has released FortiOS 5.0.6 to address this vulnerability. If you are unable to upgrade, please consider the following workaround.

Restrict access

As a general good security practice, only allow connections from trusted hosts and networks. Note that restricting access does not prevent XSS or CSRF attacks since the attack comes as an HTTP request from a legitimate user's host. Restricting access would prevent an attacker from accessing the FortiOS interface using stolen credentials from a blocked network location.