CVE-2024-14020: Carboneio Carbone RCE Vulnerability

CVE-2024-14020 Overview

A prototype pollution vulnerability has been identified in carboneio carbone, specifically affecting the lib/input.js file within the Formatter Handler component. This weakness allows attackers to manipulate object prototype attributes through improperly controlled modification mechanisms. The vulnerability can be exploited remotely, though it requires high attack complexity and is considered difficult to exploit successfully.

Critical Impact

Prototype pollution can allow attackers to modify the behavior of JavaScript objects across the application, potentially leading to denial of service, security bypass, or in specific conditions, remote code execution. A successful exploitation can "only occur if the parent NodeJS application has the same security issue."

Affected Products

• carboneio carbone versions up to commit fbcd349077ad0e8748be73eab2a82ea92b6f8a7e
• carboneio carbone versions prior to 3.5.6

Discovery Timeline

• 2026-01-07 - CVE CVE-2024-14020 published to NVD
• 2026-01-08 - Last updated in NVD database

Technical Details for CVE-2024-14020

Vulnerability Analysis

This prototype pollution vulnerability exists in the Formatter Handler component of carboneio carbone. The root issue stems from the improper initialization of the formatters object, which allowed attackers to potentially inject properties into JavaScript's Object.prototype through the __proto__ or constructor attributes.

Prototype pollution attacks occur when an attacker can inject properties into an object's prototype, affecting all objects that inherit from that prototype. In JavaScript environments like Node.js, this can have cascading effects throughout the application, potentially allowing attackers to bypass security controls, modify application logic, or cause denial of service conditions.

The attack requires network access and low privileges but has high complexity requirements. The impact is limited to confidentiality, integrity, and availability at low levels. Notably, successful exploitation is conditional—it can only fully succeed if the parent Node.js application also contains similar prototype pollution vulnerabilities.

Root Cause

The vulnerability originated from the use of a standard JavaScript object literal {} for the formatters object in lib/input.js. Standard object literals inherit from Object.prototype, making them susceptible to prototype pollution attacks where malicious input can inject properties into the prototype chain.

Attack Vector

The attack vector is network-based, allowing remote exploitation. An attacker would need to craft malicious input that manipulates the formatter handling functionality to inject prototype pollution payloads. The attack targets the prototype chain through properties like __proto__ or constructor.prototype, potentially affecting all objects in the application that rely on default prototype inheritance.

// Security patch from lib/input.js
// Before (vulnerable):
const formatters = {};

// After (fixed):
const formatters = Object.create(null); // Remove  __proto__ and constructor attributes. Mitigates prototype pollution attacks.

Source: GitHub Commit Changes

Detection Methods for CVE-2024-14020

Indicators of Compromise

• Unusual modifications to JavaScript object prototypes in application logs
• Unexpected behavior in formatter handler operations
• Anomalous input patterns containing __proto__, constructor, or prototype property names
• Application errors related to unexpected object properties

Detection Strategies

• Monitor for suspicious input payloads containing prototype pollution patterns (__proto__, constructor.prototype)
• Implement application-level logging for formatter handler inputs and outputs
• Use static analysis tools to identify prototype pollution vulnerabilities in Node.js applications
• Deploy runtime protection mechanisms that detect and block prototype pollution attempts

Monitoring Recommendations

• Enable verbose logging for carbone library operations
• Monitor Node.js application behavior for unexpected prototype modifications
• Set up alerting for error patterns related to object property access anomalies
• Review application logs for malformed input attempts targeting the formatter handler

How to Mitigate CVE-2024-14020

Immediate Actions Required

• Upgrade carboneio carbone to version 3.5.6 or later immediately
• Review parent Node.js applications for similar prototype pollution vulnerabilities
• Audit input validation and sanitization in applications using carbone
• Implement input filtering to reject payloads containing prototype pollution patterns

Patch Information

The vulnerability is resolved in carboneio carbone version 3.5.6. The fix is implemented in commit 04f9feb24bfca23567706392f9ad2c53bbe4134e, which replaces the standard object literal with Object.create(null) to create an object without prototype inheritance, effectively eliminating the prototype pollution attack surface.

For detailed patch information, see the GitHub Release Version 3.5.6 and the GitHub Commit Changes.

Workarounds

• If immediate upgrade is not possible, implement input validation to filter prototype pollution payloads
• Use Object.freeze() on critical objects to prevent modification
• Deploy a Web Application Firewall (WAF) with rules to detect prototype pollution attempts
• Ensure the parent Node.js application does not have prototype pollution vulnerabilities, as successful exploitation requires both vulnerabilities to be present

# Upgrade carbone to the patched version
npm update carbone@3.5.6

# Or install the specific patched version
npm install carbone@3.5.6 --save