This indicates an attack attempt to exploit a Information Disclosure 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 can exploit this to gain access to memory address layout, allowing them to bypass ASLR on the host machines.
Adobe Flash Player 22.214.171.1247 and earlier versions
Adobe Flash Player 126.96.36.1990 and earlier 13.x versions
Adobe Flash Player 188.8.131.529 and earlier versions for Linux
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
Apply the most recent upgrade or patch from the vendor.