CVE-2021-21220
📋 TL;DR
This vulnerability in Chrome's V8 JavaScript engine allows remote attackers to potentially execute arbitrary code via heap corruption. Attackers can exploit it by tricking users into visiting a malicious webpage. All Chrome users on versions before 89.0.4389.128 are affected.
💻 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 with full system compromise, allowing attackers to install malware, steal data, or create persistent backdoors.
Likely Case
Browser compromise leading to session hijacking, credential theft, or installation of cryptocurrency miners.
If Mitigated
Limited impact with proper sandboxing and security controls, potentially just browser crash.
🎯 Exploit Status
Multiple proof-of-concept exploits exist in public repositories. Exploitation requires user interaction (visiting malicious page).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 89.0.4389.128 and later
Vendor Advisory: https://chromereleases.googleblog.com/2021/04/stable-channel-update-for-desktop.html
Restart Required: Yes
Instructions:
1. Open Chrome. 2. Click the three-dot menu. 3. Go to Help > About Google Chrome. 4. Chrome will automatically check for and install updates. 5. Click 'Relaunch' to restart Chrome.
🔧 Temporary Workarounds
Disable JavaScript
allTemporarily disable JavaScript execution in Chrome to prevent exploitation.
chrome://settings/content/javascript
Toggle 'Allowed (recommended)' to 'Blocked'
Use Site Isolation
allEnable site isolation to limit impact of potential exploitation.
chrome://flags/#enable-site-per-process
Set to 'Enabled'
🧯 If You Can't Patch
- Use alternative browsers until patching is possible
- Implement network filtering to block known malicious domains
🔍 How to Verify
Check if Vulnerable:
Check Chrome version via chrome://settings/help or 'About Google Chrome' in menu.Check Version:
google-chrome --version (Linux) or check in Chrome settings (Windows/macOS)Verify Fix Applied:
Confirm version is 89.0.4389.128 or higher in Chrome settings.📡 Detection & Monitoring
Log Indicators:
- Chrome crash reports with V8-related errors
- Unexpected Chrome process termination
Network Indicators:
- Outbound connections to suspicious domains after visiting unknown sites
- Unusual network traffic from Chrome processes
SIEM Query:
source="chrome" AND (event_type="crash" OR process_name="chrome.exe") AND message="V8"🔗 References
- http://packetstormsecurity.com/files/162437/Google-Chrome-XOR-Typer-Out-Of-Bounds-Access-Remote-Code-Execution.html
- http://packetstormsecurity.com/files/176210/Chrome-V8-JIT-XOR-Arbitrary-Code-Execution.html
- https://chromereleases.googleblog.com/2021/04/stable-channel-update-for-desktop.html
- https://crbug.com/1196683
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EAJ42L4JFPBJATCZ7MOZQTUDGV4OEHHG/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U3GZ42MYPGD35V652ZPVPYYS7A7LVXVY/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VUZBGKGVZADNA3I24NVG7HAYYUTOSN5A/
- https://security.gentoo.org/glsa/202104-08
- http://packetstormsecurity.com/files/162437/Google-Chrome-XOR-Typer-Out-Of-Bounds-Access-Remote-Code-Execution.html
- http://packetstormsecurity.com/files/176210/Chrome-V8-JIT-XOR-Arbitrary-Code-Execution.html
- https://chromereleases.googleblog.com/2021/04/stable-channel-update-for-desktop.html
- https://crbug.com/1196683
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EAJ42L4JFPBJATCZ7MOZQTUDGV4OEHHG/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U3GZ42MYPGD35V652ZPVPYYS7A7LVXVY/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VUZBGKGVZADNA3I24NVG7HAYYUTOSN5A/
- https://security.gentoo.org/glsa/202104-08
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-21220
