Can someone please explain the logic behind calling version 3.8 the latest version? when it appears to be about 50 versions down the ladder? please see where 3.8 is on the ladder of upgrades at: https://codex.wordpress.org/WordPress_Versions
I have an installation which is 3.8 and when I go Dashboard > Updates I get told it is the latest version???
Please see screenshots - maybe I was asleep in maths class at school all those years ago.
Agree with @WebMachine – scan with WordFence to see if anything has been modified. If that doesn’t work, try disabling plugins and then the theme to isolate the issue.
I’ve seen this behaviour when developers have disabled updates in the theme. Check the file functions.php for something like: