You can upload other peoples projects to theorytab

Here is an example: Sign In - Hooktheory

This is a link to transfer a theorytab. I have found out about this because some new person started uploading other peoples tabs.

You can change the ID of the link to something else and it will let you upload it, which means you can basically upload other peoples projects.
This is a very weird bug

yeah, it’s never a good idea to have an id which is not yours, or is only generic link in the URL certainly the ownership of the project being loaded should be checked and rejected if you’re not the owner. this is the type of thing that leads to much mischief…