CVE-2021-38002 Overview
CVE-2021-38002 is a Use After Free vulnerability in the Web Transport component of Google Chrome prior to version 95.0.4638.69. This memory corruption flaw allows a remote attacker to potentially perform a sandbox escape through a specially crafted HTML page. The vulnerability exists in Chrome's implementation of the WebTransport API, which provides bidirectional transport capabilities for web applications.
Critical Impact
This vulnerability enables remote attackers to escape Chrome's sandbox protection mechanism, potentially gaining elevated privileges on the victim's system through a maliciously crafted web page.
Affected Products
- Google Chrome versions prior to 95.0.4638.69
- Fedora Project Fedora 34
- Debian Linux 10.0 and 11.0
Discovery Timeline
- 2021-11-23 - CVE-2021-38002 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2021-38002
Vulnerability Analysis
This Use After Free (CWE-416) vulnerability occurs within Chrome's Web Transport implementation. Use After Free conditions arise when a program continues to reference memory after it has been freed, leading to undefined behavior. In this case, the Web Transport component improperly manages object lifetimes, allowing an attacker to manipulate memory state through carefully constructed HTML content.
The critical nature of this vulnerability stems from its ability to enable sandbox escape. Chrome employs a multi-process architecture with sandbox isolation to contain the impact of security vulnerabilities. However, CVE-2021-38002 allows attackers to bypass these protections, potentially gaining code execution outside the sandboxed renderer process.
Root Cause
The vulnerability originates from improper memory management in the Web Transport API implementation. When certain objects are freed during WebTransport operations, references to these objects may still exist and be subsequently accessed. This dangling pointer condition can be triggered through specific sequences of operations initiated by malicious JavaScript code within a crafted HTML page.
Attack Vector
The attack requires user interaction, specifically visiting a malicious webpage or being redirected to one. The attack vector is network-based, with the attacker hosting or injecting a crafted HTML page containing malicious content that exploits the Use After Free condition. Upon successful exploitation:
- The victim visits the attacker-controlled webpage
- Malicious JavaScript triggers the Use After Free condition in Web Transport
- The attacker gains control of freed memory through heap manipulation
- The corrupted memory state enables sandbox escape
- Arbitrary code execution may occur outside Chrome's sandbox
The vulnerability is particularly dangerous because sandbox escape allows attackers to interact directly with the underlying operating system, bypassing Chrome's security boundaries.
Detection Methods for CVE-2021-38002
Indicators of Compromise
- Unusual Chrome renderer process crashes or unexpected behavior when visiting web pages
- Suspicious network connections originating from Chrome to unknown destinations
- Anomalous child processes spawned by Chrome browser processes
- Memory access violations logged in system crash reports
Detection Strategies
- Monitor for Chrome versions prior to 95.0.4638.69 in your environment using software inventory tools
- Implement network monitoring to detect connections to known malicious infrastructure
- Deploy endpoint detection solutions to identify suspicious process behavior following Chrome exploitation
- Review crash dumps and error reports for patterns consistent with Use After Free exploitation
Monitoring Recommendations
- Enable Chrome's built-in Safe Browsing protection to block known malicious pages
- Configure SIEM rules to alert on Chrome-related crash events across endpoints
- Monitor for unusual WebTransport API usage patterns in network traffic analysis
- Implement browser extension policies to restrict access to potentially malicious sites
How to Mitigate CVE-2021-38002
Immediate Actions Required
- Update Google Chrome to version 95.0.4638.69 or later immediately
- Verify Chrome auto-update functionality is enabled and functioning correctly
- Deploy updated Chrome packages through enterprise software management systems
- Audit all systems for vulnerable Chrome versions and prioritize remediation
Patch Information
Google released a security update addressing CVE-2021-38002 on October 28, 2021. The patch is included in Chrome version 95.0.4638.69 and all subsequent releases. Organizations should reference the Google Chrome Stable Channel Update Announcement for complete patch details. Additional security advisories have been issued by distribution maintainers, including the Debian Security Advisory DSA-5046 for Debian Linux users.
Workarounds
- Restrict access to untrusted websites through web filtering or proxy solutions until patching is complete
- Consider temporarily disabling WebTransport functionality via Chrome enterprise policies if business requirements permit
- Implement network segmentation to limit potential impact of sandbox escape exploitation
- Enable Chrome's Site Isolation feature for additional process-level protection
# Verify Chrome version on Linux systems
google-chrome --version
# Update Chrome on Debian/Ubuntu
sudo apt update && sudo apt upgrade google-chrome-stable
# Update Chrome on Fedora
sudo dnf update chromium
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
