To be or not be 1.5.1.2?

are you sure you mean 1.5.1.2? I believe 1.5.1.1 was just released, was it not?

Open wp-includes/version.php. That will tell you the correct version #.

@jinsan:
https://www.ads-software.com/support/topic/34867

Check out this link https://www.ads-software.com/development/2005/05/security-update/

No need to download the entire thing — its just a one line addition in the “template-functions-category.php” file.