CVE-2021-22930: Node.js Use After Free Vulnerability

CVE-2021-22930 Overview

CVE-2021-22930 is a use after free vulnerability affecting Node.js versions before 16.6.0, 14.17.4, and 12.22.4. This memory corruption flaw allows remote attackers to potentially exploit freed memory regions to manipulate process behavior, leading to arbitrary code execution or application crashes.

Critical Impact

Remote attackers can exploit this use after free vulnerability to corrupt memory and alter process behavior, potentially achieving remote code execution without authentication.

Affected Products

• Node.js versions prior to 16.6.0 (Current release line)
• Node.js versions prior to 14.17.4 (LTS)
• Node.js versions prior to 12.22.4 (LTS)
• NetApp NextGen API
• Siemens SINEC Infrastructure Network Services
• Debian Linux 10.0

Discovery Timeline

• 2021-10-07 - CVE-2021-22930 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-22930

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a class of memory corruption vulnerabilities that occur when a program continues to reference memory after it has been freed. In the context of Node.js, this flaw enables attackers to exploit the memory corruption to alter process behavior in unintended ways.

The use after free condition occurs when the Node.js runtime frees a memory allocation but retains a reference (dangling pointer) to that memory region. Subsequent operations that dereference this pointer may read or write to memory that has been reallocated for other purposes, creating an opportunity for attackers to inject malicious data or redirect program execution.

The network-accessible nature of this vulnerability means that exploitation can occur remotely without requiring user interaction or prior authentication, making it particularly dangerous for internet-facing Node.js applications and services.

Root Cause

The root cause is improper memory management within the Node.js runtime where memory is freed prematurely while references to that memory still exist in the application. This creates a dangling pointer scenario where subsequent accesses to the freed memory can lead to undefined behavior.

When the freed memory is reallocated for a different purpose, the dangling pointer now references data controlled by other parts of the application or potentially attacker-controlled input. Attackers can leverage this condition to overwrite critical data structures, function pointers, or other sensitive memory regions.

Attack Vector

The attack vector is network-based, requiring no privileges or user interaction for successful exploitation. An attacker can craft malicious requests or inputs that trigger the use after free condition in vulnerable Node.js instances.

The exploitation typically involves the following sequence:

1. An attacker sends specially crafted input to a Node.js application
2. The input triggers a code path that frees memory prematurely
3. The attacker sends additional requests to cause memory reallocation
4. The reallocated memory is filled with attacker-controlled data
5. When the dangling pointer is dereferenced, it operates on attacker-controlled data

The vulnerability was reported through the HackerOne bug bounty platform, with details available in HackerOne Report #1238162. For additional technical context, refer to the Node.js Vulnerability Blog Post.

Detection Methods for CVE-2021-22930

Indicators of Compromise

• Unexpected Node.js process crashes or segmentation faults indicating memory corruption
• Unusual memory allocation patterns or memory leak symptoms in Node.js applications
• Anomalous process behavior such as unexpected network connections or file system access
• Evidence of exploitation attempts in application logs showing malformed requests

Detection Strategies

• Implement version checking to identify Node.js installations running vulnerable versions (prior to 16.6.0, 14.17.4, or 12.22.4)
• Deploy memory sanitizers (AddressSanitizer, MemorySanitizer) in development and testing environments to detect use after free conditions
• Utilize SentinelOne's behavioral AI engine to detect memory corruption exploitation attempts
• Monitor for process memory anomalies that may indicate heap corruption or dangling pointer exploitation

Monitoring Recommendations

• Enable comprehensive application logging to capture request details that may trigger the vulnerability
• Implement runtime application self-protection (RASP) solutions to detect memory corruption in real-time
• Deploy network monitoring to identify exploitation attempts targeting Node.js services
• Configure alerting for unexpected Node.js process terminations or restarts

How to Mitigate CVE-2021-22930

Immediate Actions Required

• Upgrade Node.js immediately to patched versions: 16.6.0 or later, 14.17.4 or later, or 12.22.4 or later
• Inventory all systems running Node.js to identify vulnerable installations
• Prioritize patching for internet-facing Node.js applications and services
• Review security advisories from affected third-party vendors (Siemens, NetApp, Debian)

Patch Information

The Node.js team released security patches in July 2021 addressing this vulnerability. The official security advisory and patch details are available in the Node.js Vulnerability Blog Post.

For Siemens products, refer to Siemens Security Advisory SSA-389290. NetApp customers should consult NetApp Security Advisory NTAP-20211112-0002. Debian users can find package updates in the Debian LTS Announcement.

Workarounds

• Implement network segmentation to limit exposure of vulnerable Node.js services
• Deploy a Web Application Firewall (WAF) to filter potentially malicious requests
• Restrict network access to Node.js services to trusted IP ranges where possible
• Consider containerization with read-only file systems to limit post-exploitation impact

# Verify current Node.js version
node --version

# Update Node.js using nvm (Node Version Manager)
nvm install 16.6.0
nvm use 16.6.0

# For systems using package managers, update to latest patched version
# Debian/Ubuntu
apt-get update && apt-get upgrade nodejs

# RHEL/CentOS
yum update nodejs