This indicates an attack attempt to exploit a Code Execution vulnerability in Adobe Flash Player.
The vulnerability is due to an error when the vulnerable software handles a maliciously crafted SWF file. A remote attacker may be able to exploit this to execute arbitrary code on vulnerable systems, via a crafted SWF file.
Adobe Flash Player Desktop Runtime 126.96.36.199 and earlier Versions for Windows and Macintosh
Adobe Flash Player Extended Support Release 188.8.131.52 and earlier Versions for Windows and Macintosh
Adobe Flash Player for Google Chrome 184.108.40.206 and earlier Versions for Windows, Macintosh, Linux and ChromeOS
Adobe Flash Player for Microsoft Edge and Internet Explorer 11 220.127.116.11 and earlier Versions for Windows 10
Adobe Flash Player for Internet Explorer 10 and 11 18.104.22.168 and earlier Versions for Windows 8.0 and 8.1
Adobe Flash Player for Linux 22.214.171.1245 and earlier Versions for Linux
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.