The vulnerability stems from missing sandbox protection in three specific Groovy language constructs: constructors, instance variable initializers, and instance initializers. The CpsTransformer class in workflow-cps is responsible for AST transformations that implement CPS execution model and sandboxing.

1. visitConstructorOrMethod would handle constructor definitions - without sandbox interceptor wrapping, constructor bodies could execute arbitrary code
2. visitField processes field declarations with initializers - vulnerable when initializer expressions weren't sandboxed
3. parseScript is the entry point where these vulnerabilities would manifest during script execution

Confidence is medium as we're inferring implementation details from vulnerability description rather than explicit patch diffs, but these are the canonical components handling the vulnerable code structures based on Jenkins Pipeline architecture.