Root Cause Analysis: Looking at the given vulnerable code line and its context, the CWE-401 (Missing Release of Memory after Effective Lifetime) vulnerability exists in the code because the `destination` buffer is allocated memory using `calloc` at line 6, but this allocated memory is not freed before the function returns at line 30. The `strcpy` operation at line 29 copies the contents of `destination` into `source`, but it does not release the memory allocated for `destination`. This can lead to memory leaks and potential resource exhaustion issues.