This indicates an attack attempt against a Cross-Site Request Forgery vulnerability in Adobe Flash Player.
The vulnerability is due to the user input filters failing to properly sanitize the parameter value that is passed to flash player. An attacker can exploit this by tricking an unsuspecting user into visiting a malicious webpage, and gain unauthorized access to sensitive information.
Adobe Flash Player 126.96.36.199 and earlier versions for Windows and Macintosh
Adobe Flash Player 188.8.131.528 and earlier versions for Linux
Adobe AIR 184.108.40.206 SDK and earlier versions
Adobe AIR 220.127.116.11 SDK & Compiler and earlier versions
Adobe AIR 18.104.22.168 and earlier versions for Android
System Compromise: Remote attackers can execute arbitrary script code in the context of the application.
Apply the most recent upgrade or patch from the vendor.