No, the days start counting from the availability of a patch.

I was thinking that the other definition was right and this correction was wrong.

Then I did some searching and found multiple examples of both definitions in use, making things murky.

So I turned to Merriam-Webster’s dictionary: “ of, relating to, or being a vulnerability (as in a computer or computer system) that is discovered and exploited (as by cybercriminals) before it is known to or addressed by the maker or vendor”

And of course they use an “or” to make it ambiguous as to whether the days start counting when the vulnerability becomes known, or when the vendor has addressed it.

what if a path is never released?