CVE-2021-21162
📋 TL;DR
This vulnerability is a use-after-free memory corruption flaw in Chrome's WebRTC component that allows remote attackers to potentially execute arbitrary code or cause denial of service. It affects Google Chrome versions prior to 89.0.4389.72. Users who visit malicious websites with vulnerable Chrome versions are at risk.
💻 Affected Systems
- Google Chrome
- Chromium-based browsers
📦 What is this software?
Chrome by Google
Google Chrome is the world's most popular web browser, used by over 3 billion users globally across Windows, macOS, Linux, Android, and iOS platforms. As a Chromium-based browser developed by Google, Chrome dominates the browser market with approximately 65% market share, making it a critical compon...
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⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment.
Likely Case
Browser crash/denial of service, potential information disclosure, or limited code execution in sandboxed context.
If Mitigated
No impact if Chrome is updated to patched version or if exploit attempts are blocked by security controls.
🎯 Exploit Status
Use-after-free vulnerabilities typically require careful memory manipulation but can lead to reliable exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 89.0.4389.72 and later
Vendor Advisory: https://chromereleases.googleblog.com/2021/03/stable-channel-update-for-desktop.html
Restart Required: Yes
Instructions:
1. Open Chrome. 2. Click menu (three dots) → Help → About Google Chrome. 3. Chrome will automatically check for and install updates. 4. Click 'Relaunch' to restart Chrome with the update.
🔧 Temporary Workarounds
Disable WebRTC
allDisable WebRTC functionality to prevent exploitation of this vulnerability
chrome://flags/#disable-webrtc
Set 'WebRTC' flag to 'Disabled'
Use Chrome Enterprise policies
allDeploy Chrome updates via enterprise management tools
Use Google Admin Console or GPO to force Chrome updates
🧯 If You Can't Patch
- Deploy web filtering to block known malicious sites
- Implement application whitelisting to prevent unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check Chrome version: if version is less than 89.0.4389.72, system is vulnerable.Check Version:
chrome://version/ or 'google-chrome --version' (Linux) or check in Chrome settingsVerify Fix Applied:
Confirm Chrome version is 89.0.4389.72 or higher after update.📡 Detection & Monitoring
Log Indicators:
- Chrome crash reports
- Unexpected Chrome process termination
- Memory access violation errors
Network Indicators:
- Unusual WebRTC connections
- Traffic to known exploit hosting domains
SIEM Query:
source="chrome" AND (event_type="crash" OR message="access violation")🔗 References
- https://chromereleases.googleblog.com/2021/03/stable-channel-update-for-desktop.html
- https://crbug.com/1172054
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BBT54RKAE5XLMWSHLVUKJ7T2XHHYMXLH/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FE5SIKEVYTMDCC5OSXGOM2KRPYLHYMQX/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LCIDZ77XUDMB2EBPPWCQXPEIJERDNSNT/
- https://security.gentoo.org/glsa/202104-08
- https://www.debian.org/security/2021/dsa-4886
- https://chromereleases.googleblog.com/2021/03/stable-channel-update-for-desktop.html
- https://crbug.com/1172054
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BBT54RKAE5XLMWSHLVUKJ7T2XHHYMXLH/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FE5SIKEVYTMDCC5OSXGOM2KRPYLHYMQX/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LCIDZ77XUDMB2EBPPWCQXPEIJERDNSNT/
- https://security.gentoo.org/glsa/202104-08
- https://www.debian.org/security/2021/dsa-4886
