The vulnerability is explicitly tied to the parse_yaml_query function in parser.py where unsafe yaml.load() was used. The GitHub commit diff shows this was the only function modified to fix the issue (replaced with yaml.safe_load()). Multiple sources including CVE description, GHSA advisory, and the patch commit confirm this function's unsafe deserialization was the root cause. The added security test further validates this was the attack vector by testing YAML payload rejection after the fix.