If money gets stolen from your pushka do you have to pay it back? What if you let someone that isn’t trustworthy into your house would that be considered pshia? Would it make a difference if the pushka has a specific cause because then it has tov’im?
The answer to your question will really depend on the specifics of each individual instance, person who pushka it is, if it is considered that he was negligent in his watching over the tzedakah money. If the person borrows money from the pushka then he would be chayiv if the money is stolen, because then he is considered a shomer sachar.
Tzedakah Umispat 7-18, B’orach Tzedaah17-18.