A comment on a previous answer made me think about our hotfix policy. A current project for example is used by about 300 users all around the globe. One location found a strange bug where they issued a specific number into a combobox. That resulted in a complete server error (the session was reset with a 500 http error). I was like: "Yep, hotfix asap!" However, I'm not sure anymore since this bug only affects a specific location and a specific number. Commonly I didn't care too much and just hotfixed it. Since this question Hotfixing with an open release branch while this release is currently tested I decided to be a more subtile when it comes to the hotfix-decision.
Is there a rule of thumb when to use a hotfix rather than just a bugfix for the next release?