This indicates an attack attempt to exploit a Heap Buffer Overflow vulnerability in Adobe Flash Player.
The vulnerability is due to an error when the vulnerable software handles a maliciously crafted FLV file. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted FLV file.
Adobe Flash Player Desktop Runtime 126.96.36.199 and earlier
Adobe Flash Player Extended Support Release 188.8.131.522 and earlier
Adobe Flash Player for Google Chrome 184.108.40.206 and earlier
Adobe Flash Player for Internet Explorer 10 and Internet Explorer 11 220.127.116.11 and earlier
Adobe Flash Player 18.104.22.1686 and earlier
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.