This indicates an attack attempt to exploit a Use After Free 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 within the context of the application, via a crafted SWF file.
Adobe Flash Player Desktop Runtime 22.214.171.1246 and earlier on Windows and Macintosh
Adobe Flash Player Extended Support Release 126.96.36.1999 and earlier on Windows and Macintosh
Adobe Flash Player for Google Chrome 188.8.131.526 and earlier on Windows, Macintosh, Linux and ChromeOS
Adobe Flash Player for Microsoft Edge and Internet Explorer 11 184.108.40.2066 and earlier on Windows 10
Adobe Flash Player for Internet Explorer 11 220.127.116.116 and earlier on Windows 8.1
Adobe Flash Player for Linux 18.104.22.1689 and earlier on Linux
AIR Desktop Runtime 22.214.171.1240 and earlier on Windows and Macintosh
AIR SDK 126.96.36.1990 and earlier on Windows, Macintosh, Android and iOS
AIR SDK & Compiler 188.8.131.520 and earlier on Windows, Macintosh, Android and iOS
AIR for Android 184.108.40.206 and earlier on Android
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.