Apple has blocked access to older versions of Flash Player in order to avoid exposing Mac users to a recently patched vulnerability found within Adobe’s video player.

“Adobe Flash Player updates are available that address a recently identified Adobe Flash Player web plug-in vulnerability,” Apple said in a note posted to its support website(Opens in a new window) this weekend.

To protect those who have not yet installed the update, however, Apple has blocked older versions of Flash Player on Mac OS X 10.6, OS X Lion, and OS X Mountain Lion. Those who try to view Flash content on those operating systems might encounter a “Blocked Plug-in” alert. If you click on the alert, Safari will tell you that your Flash Player is out of date, and provide the opportunity to update.

As PCMag’s Security Watch noted, Adobe patched the security flaws in its Flash Player last week. At issue were two zero-day vulnerabilities that targeted Mozilla Firefox users by tricking them into clicking links to websites that were hosting malicious Flash files. The update, however, affected all versions of Flash on Windows, Mac OS X, and Linux.

Specifically, Adobe said in its security advisory(Opens in a new window), users of Adobe Flash Player 11.6.602.167 and earlier versions for Macintosh should update to Adobe Flash Player 11.6.602.171.

The Flash update is the second out-of-band patch for Flash Player this month, the third Adobe patch in the month of February, and fourth such patch released in 2013 so far, Security Watch said.