Process-memory corruption via unbounded username input

Buffer overflow in the login function in SourceCodester Telecom Billing Management System 1.0 allows local users to corrupt process memory. The login() function reads uname with scanf into a 10-byte character buffer without a field-width limit, so longer input writes past the buffer. Exploitation requires local interaction with the running desktop application's login flow; the public demonstration disables GS and SDL and shows memory corruption only, not code execution or a crash.