Forge 1.20.1-47.3.x
Storage Drawers 1.20.1-12.9.13
There is an exploit that exisits with the creative vending upgrade. I have a modpack that is is an expert pack and it adds a complicated recipe for the creative vending upgrade. Normally, you cannot store the upgrade in the drawer, but you can hopper or pipe the upgrade into the drawer, lock it, remove the creative vending upgrade, and then apply the upgrade to the drawer. This then gives the player infinity creative vending upgrades. Is there a way to prevent this, or a way to blacklist items from being able to enter storage drawers?
This applies to all versions of storage drawers as far as I am aware.

This is fixed in the latest versions via the addition of a blacklist option in the config. The vending upgrade is the only item in that list by default.

The statement "you cannot store the upgrade in the drawer" is incorrect. But yes, when you click on a drawer it will priotise putting the upgrade into the upgrade slots when putting them in there by hand. On the Curseforge page for the mod, they even have images of upgrades in drawers, if you were not intended to store them, why would they even show it?
As for the part about a creative vending upgrade being able allow you to infinitely take out items from the drawer is what that item is meant to do? It is a creative item that allows infinity amounts of any items, it's not a bug and it's not really an exploit as it's not obtainable normally.