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Project	Deployment	Review	Updated (UTC)
docs	Ready	Preview, Comment	Dec 15, 2025 9:27pm

Greptile Overview

Greptile Summary

This PR replaces the Node.js vm module with the isolated-vm package for remote code execution (RCE), providing a significant security improvement.

Key Changes:

• Introduces executeInIsolatedVM() function using isolated-vm v6.0.2 which creates true V8 isolates with 128MB memory limit
• Provides proper sandboxing that prevents prototype chain escape attacks (e.g., this.constructor.constructor("return process")())
• Implements secure fetch bridge using ivm.Reference for async callbacks with existing SSRF validation
• Sets up console.log/error/warn/info via ivm.Callback for stdout capture
• Blocks dangerous globals (process, require, module, etc.) using non-writable/non-configurable property definitions
• Maintains E2B integration for Python code and JavaScript with imports

Security Improvements:

• True V8 isolate separation prevents Node.js API access from sandboxed code
• Memory limits prevent resource exhaustion attacks
• Timeout enforcement for execution time limits
• SSRF protection maintained in the new secureFetch wrapper

Confidence Score: 4/5

• This PR is a well-structured security improvement that replaces a potentially vulnerable sandbox with a more secure isolation mechanism.
• Score of 4 reflects solid implementation with proper security controls (SSRF validation, memory limits, timeout handling, global blocking). Minor considerations around error handling edge cases but overall low risk.
• Pay attention to apps/sim/lib/execution/isolated-vm.ts for the core sandboxing logic.

Important Files Changed

File Analysis

Sequence Diagram

sequenceDiagram
    participant Client
    participant Route as POST /api/function/execute
    participant IsolatedVM as executeInIsolatedVM
    participant Isolate as V8 Isolate
    participant SecureFetch as secureFetch

    Client->>Route: POST { code, params, envVars, ... }
    Route->>Route: Resolve variables in code
    Route->>IsolatedVM: Execute code request
    
    IsolatedVM->>Isolate: Create V8 Isolate (128MB limit)
    IsolatedVM->>Isolate: Create context
    IsolatedVM->>Isolate: Set up globals (params, envVars, console)
    IsolatedVM->>Isolate: Set up __fetchRef callback
    IsolatedVM->>Isolate: Run bootstrap (console, fetch, block globals)
    IsolatedVM->>Isolate: Compile and run user code

    alt User code calls fetch
        Isolate->>SecureFetch: __fetchRef.apply(url, options)
        SecureFetch->>SecureFetch: validateProxyUrl (SSRF check)
        SecureFetch-->>Isolate: JSON response
    end

    alt Success
        Isolate-->>IsolatedVM: JSON result
        IsolatedVM-->>Route: { result, stdout }
        Route-->>Client: 200 { success: true, output }
    else Error
        Isolate-->>IsolatedVM: Error info
        IsolatedVM-->>Route: { error, stdout }
        Route->>Route: Format enhanced error
        Route-->>Client: 500 { success: false, error }
    end

    IsolatedVM->>Isolate: dispose()