This indicates an attack attempt to exploit a Out of Bound read 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 access sensitives data, via a crafted SWF file.
Adobe Flash Player Desktop Runtime 188.8.131.52 on Windows and Macintosh
Adobe Flash Player for Google Chrome 184.108.40.206 on Windows, Macintosh, Linux and ChromeOS
Adobe Flash Player for Microsoft Edge and Internet Explorer 11 220.127.116.11 on Windows 10 and 8.1
Adobe Flash Player for Linux 18.104.22.168 on Linux
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems
Apply the most recent upgrade or patch from the vendor.