source: https://www.securityfocus.com/bid/15537/info

OTRS is prone to multiple input-validation vulnerabilities. These issues are due to a failure in the application to properly sanitize user-supplied input.

The application is prone to multiple SQL-injection vulnerabilities, an HTML-injection vulnerability, and multiple cross-site scripting vulnerabilities. 

http://www.example.com/index.pl?Action=Login&User=%27[SQL_HERE]