fix(security): prevent prototype pollution via unsanitized config path [MEDIUM]

[ericksoa]

Security Finding: Prototype Pollution via Unsanitized Config Path

Severity: MEDIUM
Reported by: FailSafe Security Researcher
Component: nemoclaw/src/commands/migration-state.ts — setConfigValue()

Description

The setConfigValue() function tokenizes a dot-separated configuration path and iteratively traverses or builds an object structure to set a value. The function did not sanitize path tokens against dangerous JavaScript property names such as __proto__, constructor, or prototype, allowing an attacker to pollute Object.prototype through a crafted snapshot manifest.

Fix

Add a denylist check (__proto__, constructor, prototype) before using each token as a property key. Throws an error if any token matches a dangerous key.

Tests

• Unsafe paths (__proto__, constructor, prototype) in both top-level and nested positions are rejected
• Prototype stays clean after rejection (no partial mutation)
• Legitimate paths still work

Supersedes #1558. Closes #1553.

Co-authored-by: failsafesecurity failsafesecurity@users.noreply.github.com
Co-authored-by: Joshua Medvinsky joshua-medvinsky@users.noreply.github.com
Co-authored-by: Carlos Villela cvillela@nvidia.com

Summary by CodeRabbit

Release Notes

• Bug Fixes
  • Configuration settings validation now properly rejects invalid path segments to ensure system integrity and stability
• Tests
  • Added comprehensive test coverage for configuration path validation, including edge cases and boundary conditions

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: ad3b9451-91b2-4c97-8b2c-95ca2cdc0d8f

📥 Commits

Reviewing files that changed from the base of the PR and between a8d0e41 and b5499bb.

📒 Files selected for processing (2)

• nemoclaw/src/commands/migration-state.test.ts
• nemoclaw/src/commands/migration-state.ts

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📝 Walkthrough

Walkthrough

Added comprehensive prototype pollution defenses to the setConfigValue function by introducing a validation layer that rejects unsafe property paths (__proto__, constructor, prototype) while allowing legitimate configuration updates. Corresponding test suite validates both rejection of unsafe paths and acceptance of safe ones.

Changes

Cohort / File(s)	Summary
Prototype Pollution Defense nemoclaw/src/commands/migration-state.ts, nemoclaw/src/commands/migration-state.test.ts	Exported setConfigValue function with added pre-validation that rejects path segments matching unsafe property names. Comprehensive test suite verifies unsafe paths throw errors and Object.prototype remains unpolluted, while safe paths function correctly.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~18 minutes

Poem

🐰 Hops with glee through proto-safe code,
No polluted objects on this typed road,
Constructor and __proto__ now barred with care,
Security tests dance through the air! ✨🛡️

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/prototype-pollution-config-path

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_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[ericksoa]

Not needed — reopened the original #1558.