This problem starts with Firefox reporting that your flash-plugin is out of date. This report looks like this and disables all flash.
Now here we can see that version 126.96.36.1990 is vulnerable. We will then check about:plugins to see if it agrees.
Again this is also reporting 188.8.131.520, so there must be a problem, but it also tells us that there is an update available. Now I run regular yum updates on this machine, and I actually noticed flash-plugin was updated just a few hours prior to seeing this alert. So lets check the installed version.
[root@ltmmattoon matthew]# yum info flash-plugin Loaded plugins: langpacks, refresh-packagekit Installed Packages Name : flash-plugin Arch : x86_64 Version : 184.108.40.2062 Release : release Size : 19 M Repo : installed From repo : adobe-flashplayer Summary : Adobe Flash Player 11.2 URL : http://www.adobe.com/downloads/ License : Commercial Description : Adobe Flash Plugin 220.127.116.112 : Fully Supported: Mozilla SeaMonkey 1.0+, Firefox 1.5+, Mozilla : 1.7.13+
Interesting 18.104.22.1682, which is higher than what Firefox is reporting. Of course Firefox has been rebooted, but lets do it again just to make sure.
Now to fix it.
$ pwd /home/matthew/.mozilla/firefox/cls7wbvm.default $ mv pluginreg.dat pluginreg.dat.bak
Restart Firefox and it will collect new data on all of its plugins, and about:plugins will start reporting the correct version.