Research In Motion has started pushing out OS 188.8.131.5212 for the BlackBerry PlayBook. The new update corrects a possible vulnerability in Adobe Flash player. Here are the official details from RIM:
On September 21st, Adobe issued an update for Adobe Flash Player, as noted in Adobe Security BulletinsAPSB-11-26, which addresses issues that can potentially affect any PC, tablet, or other device with an operating system that supports Adobe Flash.
While there are no known reports of any BlackBerry PlayBook tablet users being affected by these Adobe Flash issues, we (as always) encourage all BlackBerry PlayBook users to update to the newest version of the BlackBerry Tablet OS. For more information about what these security updates mean to the BlackBerry PlayBook, please see our security advisory.
The OS update should get pushed to your device now. Should you not see the update notification popup, you can manually check for the update in the ‘software update’ section of the options for the PlayBook.