CVE-2021-30520
📋 TL;DR
This is a use-after-free vulnerability in Google Chrome's Tab Strip component that allows heap corruption. Attackers can exploit it by convincing users to install a malicious extension and then visiting a crafted HTML page. All Chrome users prior to version 90.0.4430.212 are affected.
💻 Affected Systems
- Google Chrome
📦 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, data leakage, or limited code execution within the browser sandbox.
If Mitigated
No impact if Chrome is updated to patched version or malicious extensions are blocked.
🎯 Exploit Status
Requires social engineering to install malicious extension plus crafted web content. No public exploit code available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 90.0.4430.212 and later
Vendor Advisory: https://chromereleases.googleblog.com/2021/05/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.
🔧 Temporary Workarounds
Disable Chrome Extensions
allTemporarily disable all extensions to prevent exploitation
chrome://extensions/ → toggle off all extensions
Restrict Extension Installation
allConfigure Chrome policies to block extension installation
Windows: Configure via Group Policy
Linux: Set ExtensionInstallBlocklist policy
macOS: Use managed preferences
🧯 If You Can't Patch
- Implement application whitelisting to block malicious extensions
- Use network filtering to block suspicious HTML content delivery
🔍 How to Verify
Check if Vulnerable:
Check Chrome version: If version is less than 90.0.4430.212, system is vulnerable.Check Version:
chrome://version/ or 'google-chrome --version' (Linux)Verify Fix Applied:
Confirm Chrome version is 90.0.4430.212 or higher after update.📡 Detection & Monitoring
Log Indicators:
- Chrome crash reports with tab strip errors
- Unexpected extension installation events
Network Indicators:
- Requests to known malicious extension repositories
- Unusual outbound connections after visiting crafted pages
SIEM Query:
source="chrome" AND (event="crash" OR event="extension_install")🔗 References
- https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop.html
- https://crbug.com/1193362
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ETMZL6IHCTCTREEL434BQ4THQ7EOHJ43/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PAT6EOXVQFE6JFMFQF4IKAOUQSHMHL54/
- https://security.gentoo.org/glsa/202107-06
- https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop.html
- https://crbug.com/1193362
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ETMZL6IHCTCTREEL434BQ4THQ7EOHJ43/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PAT6EOXVQFE6JFMFQF4IKAOUQSHMHL54/
- https://security.gentoo.org/glsa/202107-06
