Programming Tutorials

  The Illusion of Internal Functions The syntactic sugar of Next.js Server Actions ( "use server" ) is dangerous. It lowers the barrier between client and server to the point where many developers forget a boundary exists at all. Because Server Actions look like standard JavaScript functions exported from a module, developers often treat them as internal logic. They assume that if an action is imported and used inside a specific Server Component, it can only be triggered by that component. This is false. Every Server Action is a public HTTP endpoint. If you do not explicitly validate inputs and verify authorization within the action itself, you are deploying an insecure API that anyone can exploit using  curl  or  fetch , regardless of your UI logic. The Root Cause: How Server Actions Compile To understand the vulnerability, you must understand the compilation output. When Next.js compiles a file with  "use server" , it does not bundle that code for the client. ...