CVE-2021-21223
📋 TL;DR
This CVE describes an integer overflow vulnerability in Chrome's Mojo IPC framework that could allow a remote attacker who has already compromised the renderer process to escape the browser sandbox. The vulnerability affects Google Chrome versions prior to 90.0.4430.85. 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
Complete system compromise via sandbox escape leading to arbitrary code execution with the privileges of the Chrome process, potentially allowing installation of malware, data theft, or system takeover.
Likely Case
Attackers combine this vulnerability with other exploits to achieve full sandbox escape and execute arbitrary code on the target system.
If Mitigated
With proper controls like Chrome's sandbox enabled and up-to-date versions, the impact is limited to the sandboxed renderer process only.
🎯 Exploit Status
Exploitation requires chaining with another vulnerability to first compromise the renderer process. The integer overflow then enables sandbox escape.
🛠️ 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 and click the three-dot menu. 2. Go to Help > About Google Chrome. 3. Chrome will automatically check for updates and install version 90.0.4430.85 or later. 4. Click 'Relaunch' to restart Chrome with the update.
🔧 Temporary Workarounds
Disable JavaScript
allPrevents initial renderer compromise by disabling JavaScript execution, though this breaks most web functionality.
🧯 If You Can't Patch
- Restrict Chrome usage to trusted websites only
- Implement application whitelisting to prevent unauthorized Chrome execution
🔍 How to Verify
Check if Vulnerable:
Check Chrome version by navigating to chrome://version/ and verifying version is below 90.0.4430.85Check Version:
google-chrome --versionVerify Fix Applied:
Confirm Chrome version is 90.0.4430.85 or higher via chrome://version/📡 Detection & Monitoring
Log Indicators:
- Chrome crash reports with sandbox violation indicators
- Unexpected Chrome child process termination
Network Indicators:
- Unusual outbound connections from Chrome processes
- Traffic to known exploit hosting domains
SIEM Query:
process_name:"chrome.exe" AND (event_id:1000 OR event_id:1001) AND description:"sandbox"🔗 References
- https://chromereleases.googleblog.com/2021/04/stable-channel-update-for-desktop_20.html
- https://crbug.com/1195308
- 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/1195308
- 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
