This page has critical misinformation which has already caused confusion on this thread.

Version number alone cannot tell you if you are vulnerable or patched! Many, many Linux distributions, including (at least) Ubuntu and RHEL "backport" security fixes to older versions of the software. That means you could be using an old version of sudo, but still fully patched and protected from this exploit.

Edit: furthermore, the patching instructions for WSL is completely wrong and should not be followed. The correct procedure is to just get the update from your distro:

sudo apt-get update && sudo apt-get --only-upgrade install sudo