Users of the Linux operating system are being urged to update it to remove a "serious" bug that hackers could use to hijack systems. (http://www.bbc.co.uk/news/technology-37728010)
Of course, millions of Android phones will never get an update to fix this because manufacturers and networks are only interested in selling new phones, not supporting users of old phones.
You may be right in that there may not be an update to fix this particular bug but I have an Android tablet and my wife has an Android phone and we do get updates from time to time.
Not sure if it was for this, but I had an update on my HTC only yesterday. It took about 40 mins, so it must have been a fairly major one.