CVE-2020-8174: Node.js Use-After-Free Vulnerability

CVE-2020-8174 Overview

A memory corruption vulnerability exists in Node.js versions prior to 10.21.0, 12.18.0, and 14.4.0 within the N-API (Node-API) string handling functions. The napi_get_value_string_*() family of functions allows various kinds of memory corruption when processing JavaScript string values. This vulnerability affects applications that use native addons built with N-API to convert JavaScript strings to native character arrays.

Critical Impact

Successful exploitation of this vulnerability could allow remote attackers to achieve arbitrary code execution, cause denial of service, or corrupt sensitive memory regions in applications using vulnerable Node.js versions. The network-accessible attack vector combined with potential for complete system compromise makes this a serious security concern.

Affected Products

• Node.js versions before 10.21.0
• Node.js versions before 12.18.0
• Node.js versions before 14.4.0
• Oracle Banking Extensibility Workbench 14.3.0 and 14.4.0
• Oracle Blockchain Platform
• Oracle MySQL Cluster
• Oracle Retail XStore Point of Service (versions 16.0.6, 17.0.4, 18.0.3, 19.0.2, 20.0.1)
• NetApp Active IQ Unified Manager
• NetApp OnCommand Insight
• NetApp OnCommand Workflow Automation
• NetApp SnapCenter

Discovery Timeline

• 2020-07-24 - CVE-2020-8174 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-8174

Vulnerability Analysis

This vulnerability resides in the N-API layer of Node.js, specifically within the napi_get_value_string_*() family of functions. These functions are used by native addons to convert JavaScript string values to native C/C++ string representations. The vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-191 (Integer Underflow).

The flaw occurs when the N-API functions fail to properly validate buffer sizes and string lengths during the conversion process. An integer underflow condition can arise when calculating the required buffer size, leading to allocation of an insufficiently sized buffer. Subsequent write operations then overflow this buffer, corrupting adjacent memory regions.

Native addons are commonly used in Node.js applications for performance-critical operations, cryptographic functions, and system-level integrations. Applications utilizing such addons that process untrusted string input are particularly vulnerable.

Root Cause

The root cause of this vulnerability is an integer underflow in the buffer size calculation within the napi_get_value_string_*() functions. When the string length calculation results in an underflow, the allocated buffer becomes smaller than the actual data being written. This leads to memory corruption as the string data overflows the allocated buffer boundaries.

The N-API string functions include napi_get_value_string_utf8(), napi_get_value_string_utf16(), and napi_get_value_string_latin1(). Each of these functions was susceptible to the same integer underflow issue when handling specially crafted string inputs.

Attack Vector

The attack vector is network-based, allowing remote exploitation without authentication or user interaction. An attacker can exploit this vulnerability by sending specially crafted input to a Node.js application that:

1. Uses native addons built with N-API
2. Processes string data from external sources (HTTP requests, WebSocket messages, file uploads)
3. Passes this string data to vulnerable napi_get_value_string_*() functions

The vulnerability manifests when malicious string input triggers the integer underflow condition during buffer allocation. The attacker does not need authenticated access, and no user interaction is required. However, exploitation requires high attack complexity as it depends on specific memory layouts and application configurations.

For technical details on the vulnerability mechanism, see the HackerOne Report #784186.

Detection Methods for CVE-2020-8174

Indicators of Compromise

• Unexpected crashes or segmentation faults in Node.js processes with native addon dependencies
• Memory corruption errors logged by application monitoring tools or crash dumps
• Unusual string processing patterns in application logs that precede service disruptions
• Core dump files indicating buffer overflow conditions in N-API related functions

Detection Strategies

• Audit Node.js installations to identify versions prior to 10.21.0, 12.18.0, or 14.4.0
• Inventory applications using native addons built with N-API and prioritize for patching
• Implement application-level input validation for string data before passing to native modules
• Deploy memory corruption detection tools (AddressSanitizer, Valgrind) in development and testing environments

Monitoring Recommendations

• Monitor Node.js process health metrics for unusual memory usage patterns or unexpected restarts
• Configure alerting for application crashes with memory corruption signatures
• Enable detailed logging for native addon function calls when processing external input
• Track process memory allocation patterns for anomalies indicative of exploitation attempts

How to Mitigate CVE-2020-8174

Immediate Actions Required

• Upgrade Node.js to version 10.21.0 or later (for 10.x branch), 12.18.0 or later (for 12.x branch), or 14.4.0 or later (for 14.x branch)
• Review and update all Oracle products to patched versions as described in Oracle security advisories
• Update NetApp products (Active IQ Unified Manager, OnCommand Insight, OnCommand Workflow Automation, SnapCenter) per vendor guidance
• Implement strict input validation at application boundaries before string data reaches native addons

Patch Information

Node.js released security updates addressing this vulnerability across all active release lines. Organizations should apply the following minimum versions:

• Node.js 10.x: Upgrade to version 10.21.0 or later
• Node.js 12.x: Upgrade to version 12.18.0 or later
• Node.js 14.x: Upgrade to version 14.4.0 or later

For Oracle products, refer to the Oracle Security Alert CPU October 2020, Oracle Security Alert CPU January 2021, Oracle Security Alert CPU July 2021, and Oracle Security Alert CPU April 2022 for product-specific patch information.

For NetApp products, consult the NetApp Security Advisory NTAP-20201023-0003 for remediation guidance.

Workarounds

• Limit exposure of Node.js applications to untrusted networks where possible
• Implement Web Application Firewall (WAF) rules to filter potentially malicious string payloads
• Run Node.js applications in sandboxed environments to contain potential exploitation impact
• Disable or remove unnecessary native addons that utilize N-API string functions

# Check current Node.js version
node --version

# Update Node.js using nvm (Node Version Manager)
nvm install 14.4.0
nvm use 14.4.0

# Verify native addon dependencies
npm ls | grep -E "native|addon|binding"