CVE-2021-21225
📋 TL;DR
This vulnerability allows remote attackers to exploit heap corruption in Chrome's V8 JavaScript engine through out-of-bounds memory access. Attackers can trigger this via specially crafted HTML pages, potentially leading to arbitrary code execution. All users running vulnerable Chrome versions are affected.
💻 Affected Systems
- Google Chrome
- Chromium-based browsers
- Microsoft Edge (Chromium-based)
- Brave
- Opera
📦 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 the same privileges as the Chrome process, potentially leading to full system compromise, data theft, or ransomware deployment.
Likely Case
Browser crash (denial of service) or limited code execution within the browser sandbox, potentially enabling credential theft or session hijacking.
If Mitigated
Browser crash with no data loss if sandboxing works correctly, or successful blocking by security controls before exploitation.
🎯 Exploit Status
Exploitation requires user interaction (visiting malicious page) but no authentication. Proof-of-concept exists in bug tracker.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 90.0.4430.85 and later
Vendor Advisory: https://chromereleases.googleblog.com/2021/04/stable-channel-update-for-desktop_20.html
Restart Required: Yes
Instructions:
1. Open Chrome settings. 2. Click 'About Chrome'. 3. Chrome will automatically check for and install updates. 4. Click 'Relaunch' to restart Chrome with the patched version.
🔧 Temporary Workarounds
Disable JavaScript
allPrevents execution of malicious JavaScript that could trigger the vulnerability
chrome://settings/content/javascript
Use Site Isolation
allEnforces process separation between websites to limit impact
chrome://flags/#enable-site-per-process (set to Enabled)
🧯 If You Can't Patch
- Use alternative browsers temporarily
- Implement network filtering to block malicious sites
🔍 How to Verify
Check if Vulnerable:
Check Chrome version in settings: chrome://settings/helpCheck Version:
google-chrome --version (Linux) or chrome://version (all platforms)Verify Fix Applied:
Confirm Chrome version is 90.0.4430.85 or higher📡 Detection & Monitoring
Log Indicators:
- Chrome crash reports
- Unexpected process termination
- Memory access violation logs
Network Indicators:
- Requests to known malicious domains hosting exploit code
- Unusual outbound connections after visiting suspicious sites
SIEM Query:
source="chrome" AND (event="crash" OR event="access_violation") AND version<"90.0.4430.85"🔗 References
- https://chromereleases.googleblog.com/2021/04/stable-channel-update-for-desktop_20.html
- https://crbug.com/1195977
- 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.debian.org/security/2021/dsa-4906
- https://chromereleases.googleblog.com/2021/04/stable-channel-update-for-desktop_20.html
- https://crbug.com/1195977
- 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.debian.org/security/2021/dsa-4906
