It's a upgrade patch. Lite version 3.15 is used to upgrade 3.12 (might work with 3.10, 3.11).
You need to ask your AV software. The patch is just a text file containing just one word. If you AV software has a problem with that, it might not worth using.
Why do you think that 3.15 would need a bug fix from 3.12? By the way, there was a 3.12 version that do not need the bug fix. The reason for keeping the bug fix is because it's much more convinient to download the bug fix patch (a few hundred kb) than downloading the fixed version (a few GB).
For 3.15, you need to fix for 3.15.