source: https://www.securityfocus.com/bid/55915/info

SilverStripe is prone to a URI-redirection vulnerability because the application fails to properly sanitize user-supplied input.

A successful exploit may aid in phishing attacks; other attacks are possible.

SilverStripe 2.4.7 and prior are vulnerable. 

http://www.example.com/index.php/Security/login?BackURL=http://example1.com