@SvenDowideit, I understand your concerns.
But I can assure you: ".. *latest* version of the Ubuntu base image .." is a jolly good and perfectly sound sentence. 
I will be keeping it due to the following reasons:

 - The sentence being clear, to the point and it putting the emphasis on versioning.

Which It does by not getting beginner level readers lost with:

 - tags,
 - optional tags,
 - versions
 - constraints
 - default latest etc.
 - why to state a tag
 - importance of full declarations.