The vulnerability stems from the install_agent function's original implementation which:

1. Used hardcoded '/tmp' work directory (world-writable)
2. Downloaded agent-install.sh to predictable path /tmp/install.sh
3. Executed scripts directly from /tmp without secure tempfile practices

The fix in commit e11298d shows migration to cachedir + tempfile.NamedTemporaryFile with delete=False, confirming the original function's insecure temp file handling was the root cause.