The actionSendErrorReport method in protected/controllers/SiteController.php in X2Engine 2.8 through 4.1.7 allows remote attackers to conduct PHP object injection and Server-Side Request Forgery (SSRF) attacks via crafted serialized data in the report parameter.
http://x2community.com/topic/1804-important-security-patch/
http://www.securityfocus.com/archive/1/533513/100/0/threaded