This indicates an attack attempt to exploit a Cross-Site Scripting vulnerability in Symantec DLP.
The vulnerability is due to insufficient sanitizing of user supplied inputs when the vulnerable software handles a maliciously crafted HTTP request. A remote attacker may be able to exploit this to execute arbitrary script code within the context of the user's browser, via a crafted HTTP request.
Symantec DLP versions 15.5 MP1 and prior
System Compromise: Remote attackers can execute arbitrary script code within the context of the target user's browser
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