CentreStack before 17.4 contains a session variable injection vulnerability that allows unauthenticated attackers to inject arbitrary session variables by embedding newline and tab characters into a crafted AccountName parameter posted to the SelectProvider.aspx endpoint. Attackers can exploit the lack of input sanitization in the custom session serialization format to inject a resellerid session variable, bypassing the IsValidRSession authentication check and gaining unauthorized access to management pages.