source: https://www.securityfocus.com/bid/9841/info

Multiple vendor Internet Browsers have been reported to be prone to a cookie path argument restriction bypass vulnerability. The issue presents itself due to a failure to properly sanitize encoded URI content, this may make it possible for an attacker to craft a URI that will contain encoded directory traversal sequences sufficient to provide access to a supposedly path exclusive cookie from an alternate path.

http://www.example.com/secure/%2e%2e/sample/insecure.cgi?xss=<golarge>