CVE-2021-21188
📋 TL;DR
This is a use-after-free vulnerability in Chrome's Blink rendering engine that allows remote attackers to potentially execute arbitrary code via a crafted HTML page. It affects all Chrome users prior to version 89.0.4389.72. Successful exploitation could lead to complete system compromise.
💻 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 full system compromise, data theft, or ransomware deployment
Likely Case
Browser crash or limited code execution in sandboxed context
If Mitigated
Browser crash with no code execution due to sandboxing
🎯 Exploit Status
Exploitation requires user to visit malicious website. No public exploit code available at disclosure.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 89.0.4389.72
Vendor Advisory: https://chromereleases.googleblog.com/2021/03/stable-channel-update-for-desktop.html
Restart Required: Yes
Instructions:
1. Open Chrome menu > Help > About Google Chrome. 2. Chrome will automatically check for updates. 3. If update available, click 'Relaunch' to apply. 4. Verify version is 89.0.4389.72 or later.
🔧 Temporary Workarounds
Disable JavaScript
allPrevents exploitation by disabling JavaScript execution
chrome://settings/content/javascript > Block
Use Site Isolation
allEnhances sandboxing between websites
chrome://flags/#site-isolation-trial-opt-out > Disabled
🧯 If You Can't Patch
- Restrict browsing to trusted websites only
- Implement network filtering to block malicious domains
🔍 How to Verify
Check if Vulnerable:
Check Chrome version in menu > Help > About Google ChromeCheck Version:
google-chrome --version (Linux) or chrome://version (all platforms)Verify Fix Applied:
Confirm version is 89.0.4389.72 or later📡 Detection & Monitoring
Log Indicators:
- Chrome crash reports
- Unexpected process termination
Network Indicators:
- Connections to suspicious domains hosting HTML pages
SIEM Query:
source="chrome" AND (event="crash" OR event="process_termination")🔗 References
- https://chromereleases.googleblog.com/2021/03/stable-channel-update-for-desktop.html
- https://crbug.com/1161739
- 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/1161739
- 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
