The vulnerability stems from unsafe YAML deserialization. The advisory explicitly states the parser wasn't restricted to safe types. In Java/YAML ecosystems (e.g., SnakeYAML), this typically manifests when using Yaml.load() without a restricted constructor. The KubernetesEngineBuilder class would logically handle YAML input during build steps, and the patch in 0.8.1 would have added a type-safe constructor configuration here. While exact method names aren't visible without code diffs, the pattern matches CWE-502 exploitation vectors in YAML parsing contexts.