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