Imperva SecureSphere Web Application Firewall and Database Firewall products can be bypassed by appending specially crafted data to requests. Protection provided by the Imperva device against attacks such as SQL injection and Cross-Site Scripting is negated, allowing unfiltered requests through to protected applications.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/88386/CSS10-01.txt
Source: https://packetstormsecurity.com/files/88386/Imperva-SecureSphere-Bypass.html