Root Cause Analysis: Looking at the given vulnerable code line and its context, the CWE-787 (out-of-bounds write) vulnerability exists in the code because the `cc->tfms` array is allocated without first checking whether `cc->tfms_count` is 0. If `cc->tfms_count` is 0, then allocating memory for `cc->tfms` will result in an out-of-bounds write vulnerability, which is CWE-787.