🛡️ Sentinel: [CRITICAL] Fix prototype pollution in label tracking

[ericbfriday]

🚨 Severity: CRITICAL
💡 Vulnerability: The Lua parser tracked script labels using a simple object literal (labels: {}). This allowed malicious users to define labels matching generic object prototype properties (like __proto__ or hasOwnProperty), potentially polluting or interfering with the Object.prototype when accessed or modified during the goto resolution phase.
🎯 Impact: This could allow a malicious user to overwrite the global Object.prototype chain during parsing, causing the host application to crash, leak information, or behave unexpectedly.
🔧 Fix: Modified the label tracking dictionary initialization in luaparse.js to Object.create ? Object.create(null) : {}, which ensures the dictionary has no prototype chain.
✅ Verification: Ran npm run test and npm run bench:luast to verify that functionality and performance are maintained. Evaluated a manual test script testing parsing ::__proto__:: showing it successfully parses without polluting Object.prototype.

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PR created automatically by Jules for task 17589926056849892677 started by @ericbfriday

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[Copilot]

Pull request overview

This PR mitigates a prototype-pollution vector in luaparse’s control-flow label tracking by ensuring label dictionaries don’t inherit from Object.prototype, preventing special keys like __proto__ from mutating the dictionary’s prototype during parsing.

Changes:

• Initialize per-scope labels with a null-prototype object (Object.create(null)) instead of an object literal.
• Add a Sentinel record documenting the vulnerability and the preferred prevention pattern for dictionary-like objects.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
luaparse.js	Hardens label tracking storage against prototype pollution by using a null-prototype dictionary.
.jules/sentinel.md	Documents the vulnerability and the mitigation guidance for future prevention.

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