This indicates an attack attempt to exploit a Use-After-Free vulnerability in Adobe Flash.
The vulnerability is due to an error when the vulnerable software attempts to access an object that has been deleted. 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 220.127.116.11 and earlier for Windows and Macintosh
Adobe Flash Player Extended Support Release 18.104.22.1688 and earlier for Windows and Macintosh
Adobe Flash Player for Google Chrome 22.214.171.124 and earlier for Windows, Macintosh, Linux and ChromeOS
Adobe Flash Player for Microsoft Edge and Internet Explorer 11 126.96.36.199 and earlier for Windows 10
Adobe Flash Player for Internet Explorer 10 and 11 188.8.131.52 and earlier for Windows 8.0 and 8.1
Adobe Flash Player for Linux 184.108.40.2064 and earlier for Linux
AIR Desktop Runtime 220.127.116.11 and earlier for Windows and Macintosh
AIR SDK 18.104.22.168 and earlier for Windows, Macintosh, Android and iOS
AIR SDK & Compiler 22.214.171.124 and earlier for Windows, Macintosh, Android and iOS
AIR for Android 126.96.36.199 and earlier for Android
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.