I was on Mountain Lion and Firefox whined that current flash player was vulnerable. However, I couldn't seems to get a regular setup file to work properly.
I've tried to install many times, including doing uninstaller and reinstalling. Nothing worked. It always didn't response to mouse cursor at an auto-update choices dialog.
Solution: Download offline setup file from http://www.adobe.com/products/flashplayer/distribution3.html and everything will be fine once again. I surely hope Adobe addresses this soon.