CVE-2021-4102 Overview
CVE-2021-4102 is a use after free vulnerability in the V8 JavaScript engine used by Google Chrome prior to version 96.0.4664.110. This memory corruption flaw allows a remote attacker to potentially exploit heap corruption via a crafted HTML page. The vulnerability is classified as CWE-416 (Use After Free) and has been confirmed as actively exploited in the wild, leading to its inclusion in CISA's Known Exploited Vulnerabilities (KEV) catalog.
Critical Impact
This vulnerability enables remote code execution through heap corruption when a user visits a malicious webpage, with confirmed active exploitation in the wild.
Affected Products
- Google Chrome versions prior to 96.0.4664.110
- All platforms running vulnerable Chrome versions (Windows, macOS, Linux)
- Chromium-based browsers using the affected V8 engine version
Discovery Timeline
- December 13, 2021 - Google releases security patch in Chrome version 96.0.4664.110
- February 11, 2022 - CVE-2021-4102 published to NVD
- October 24, 2025 - Last updated in NVD database
Technical Details for CVE-2021-4102
Vulnerability Analysis
This use after free vulnerability resides in Google Chrome's V8 JavaScript engine, which is responsible for executing JavaScript code within the browser. The flaw occurs when memory that has been freed is subsequently accessed, leading to heap corruption conditions that can be exploited by attackers.
When a user navigates to a specially crafted HTML page, the malicious code can trigger the use after free condition within V8's memory management routines. This allows an attacker to manipulate heap memory in a way that could lead to arbitrary code execution within the context of the browser process. The vulnerability requires user interaction (visiting a malicious page) but can be exploited remotely over the network with no authentication required.
Root Cause
The vulnerability stems from improper memory lifecycle management within the V8 JavaScript engine. A use after free condition occurs when code continues to reference memory after it has been deallocated, creating a scenario where the freed memory location could be reallocated for different purposes while still being referenced by the vulnerable code path.
Attack Vector
The attack vector for CVE-2021-4102 is network-based, requiring a victim to visit an attacker-controlled or compromised webpage containing the malicious payload. The exploitation process involves:
- Victim navigates to a crafted HTML page containing malicious JavaScript
- The JavaScript triggers the use after free condition in V8
- Attacker achieves heap corruption and potentially arbitrary code execution
- The attacker gains code execution within the Chrome renderer process sandbox
The vulnerability manifests within V8's internal memory handling routines. When JavaScript code triggers certain operations in a specific sequence, memory may be freed prematurely while references to that memory still exist. Subsequent access to this freed memory leads to heap corruption that can be leveraged for exploitation. For detailed technical information, refer to Chromium Bug Report #1278387.
Detection Methods for CVE-2021-4102
Indicators of Compromise
- Unusual Chrome process behavior or unexpected crashes
- Detection of known exploit payloads targeting V8 in network traffic
- JavaScript execution patterns consistent with heap spray techniques
- Anomalous memory allocation patterns in Chrome renderer processes
Detection Strategies
- Monitor for Chrome versions prior to 96.0.4664.110 across the enterprise
- Deploy endpoint detection rules for V8 exploitation patterns and heap corruption attempts
- Implement network monitoring for traffic to known malicious domains serving exploits
- Enable Chrome's built-in security telemetry and crash reporting
Monitoring Recommendations
- Audit all Chrome installations and ensure automatic updates are enabled
- Monitor security advisories from Google Chrome for related vulnerabilities
- Track CISA KEV catalog updates for additional exploitation intelligence
- Review endpoint logs for suspicious JavaScript execution or browser crashes
How to Mitigate CVE-2021-4102
Immediate Actions Required
- Update Google Chrome to version 96.0.4664.110 or later immediately
- Enable automatic updates for Chrome to receive future security patches
- Consider restricting browser access to untrusted websites until patching is complete
- Verify all Chromium-based browsers in the environment are also updated
Patch Information
Google addressed this vulnerability in the Chrome 96.0.4664.110 stable channel update released on December 13, 2021. The security fix resolves the use after free condition in the V8 JavaScript engine. Organizations should update to the latest stable Chrome version to ensure protection against this and subsequent vulnerabilities. Refer to the Google Chrome Update Blog for official patch details.
Workarounds
- Implement network-level filtering to block known malicious domains serving exploits
- Enable Chrome's Site Isolation feature for additional process-level sandboxing
- Consider using browser isolation solutions for high-risk browsing activities
- Deploy web content filtering to restrict access to untrusted or unknown websites
# Verify Chrome version on Windows
"C:\Program Files\Google\Chrome\Application\chrome.exe" --version
# Verify Chrome version on macOS/Linux
google-chrome --version
# Force Chrome update via enterprise deployment
# Windows Group Policy: Update Chrome to 96.0.4664.110 or later
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
