I have a Debian x86_64 system with Firefox installed from Mozilla's tar.gz.
On the addons page (hit CONTROL+SHIFT+A then go to the Plugins tab) there is a link: "Check to see if your plugins are up to date." When I click on it displays: Shockwave Flash 11.2 r202 vulnerable. When I click on "Update now" the version presented to me to download is:
Adobe Flash Player version 18.104.22.1681 Your system: Linux 64-bit, Firefox
Which is the same I already have.
The version string in Add-ons Manager's Plugin tab is: Shockwave Flash 11,2,202,291
# /usr/sbin/update-flashplugin-nonfree --status Flash Player version installed on this system : 22.214.171.1241 Flash Player version available on upstream site: 126.96.36.1991 flash-mozilla.so - auto mode link currently points to /usr/lib/flashplugin-nonfree/libflashplayer.so /usr/lib/flashplugin-nonfree/libflashplayer.so - priority 50 Current 'best' version is '/usr/lib/flashplugin-nonfree/libflashplayer.so'.