This indicates an attack attempt against a Cross Site Scripting vulnerability in Peakflow SP.
The vulnerability is caused by an error when the vulnerable software handles malicious HTTP requests. It allows a remote attacker to execute arbitrary script via sending a crafted HTTP request.
Arbor Networks Peakflow SP 3.6.1
Arbor Networks Peakflow SP 0
System Compromise: Remote attackers can execute arbitrary script code in the context of the affected site.
Upgrade to Peakflow SP releases 5.1.1 patch 6.