According to the Adobe security advisory, the flaw is being actively exploited in the wild, but apart from crediting its discovery to researchers Alexander Polyakov and Anton Ivanov of Kaspersky Lab, no details about the ongoing attack has been shared.
A post published on Monday on Kaspersky Lab's Securelist blog reveals that their researchers have uncovered a new sophisticated cyberespionage operation that, among other things, was able to compromise Macs and computers running Linux.
It seems probable that the Flash flaw is among the ones leveraged by the attackers, but we won't know for sure until more details about this operation are shared next week.
But you shouldn't wait to implement the fix. If you use Adobe Flash Player 188.8.131.52 and earlier versions for Windows and Macintosh or Adobe Flash Player 184.108.40.2065 and earlier versions for Linux, visit Adobe's Flash Player Download Center and pick it up.
If you use Flash embedded in Chrome or Internet Explorer, update your browser to the newest, non-vulnerable versions.
UPDATE: Kaspersky Lab researchers have released additional technical details about the exploits that target this vulnerability and the payload they deliver.