This indicates an attack attempt to exploit a Cross-Site Scripting vulnerability in Joomla! Barter Sites Component.
The vulnerability is due to insufficient sanitizing of user-supplied inputs in the application. An authenticated remote attacker may be able to exploit this to execute arbitrary script code within the context of the application.
Joomla! Barter Sites Component 1.3
System Compromise: Remote attackers can execute arbitrary script code in the context of the affected system.
Currently we are unaware of any vendor supplied patch for this issue.