Root Cause Analysis: The CWE-401 (Missing Release of Memory after Effective Lifetime) vulnerability exists in the code because the dynamically allocated memory for `destination` using `calloc` at line 6 is not released after its effective lifetime. The `destination` pointer is allocated memory, and it is used until the end of the function. However, there is no corresponding `free` call to deallocate the memory before the function returns. This can lead to memory leakage, which is a violation of CWE-401.