CVE-2021-37981
📋 TL;DR
CVE-2021-37981 is a heap buffer overflow vulnerability in Chrome's Skia graphics engine that allows an attacker who has already compromised the renderer process to potentially escape the browser sandbox. This affects users running Chrome versions prior to 95.0.4638.54. Successful exploitation could lead to full system compromise.
💻 Affected Systems
- Google Chrome
- Chromium-based browsers
- Microsoft Edge (Chromium-based)
- Brave Browser
- 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...
Learn more about Chrome →⚠️ Risk & Real-World Impact
Worst Case
Complete sandbox escape leading to arbitrary code execution with system-level privileges, potentially allowing full control of the affected system.
Likely Case
Sandbox escape enabling installation of malware, data theft, or persistence mechanisms on the compromised system.
If Mitigated
Limited to renderer process compromise only, with sandbox preventing system-level access.
🎯 Exploit Status
Requires chaining with another vulnerability to first compromise the renderer process, then this vulnerability enables sandbox escape.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 95.0.4638.54 and later
Vendor Advisory: https://chromereleases.googleblog.com/2021/10/stable-channel-update-for-desktop_19.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 with the update.
🔧 Temporary Workarounds
Disable JavaScript
allPrevents exploitation by disabling JavaScript execution, though this breaks most web functionality.
chrome://settings/content/javascript
Use Site Isolation
allEnsure site isolation is enabled to limit impact of renderer compromise.
chrome://flags/#site-isolation-trial-opt-out (set to Disabled)
🧯 If You Can't Patch
- Restrict browser usage to trusted websites only
- Implement application whitelisting to prevent unauthorized browser execution
🔍 How to Verify
Check if Vulnerable:
Check Chrome version by navigating to chrome://version and verifying version is below 95.0.4638.54Check Version:
On Windows: "C:\Program Files\Google\Chrome\Application\chrome.exe" --version
On Linux: google-chrome --version
On macOS: /Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --versionVerify Fix Applied:
Confirm Chrome version is 95.0.4638.54 or higher via chrome://version📡 Detection & Monitoring
Log Indicators:
- Chrome crash reports with Skia-related stack traces
- Unexpected Chrome renderer process termination
- Sandbox policy violation logs
Network Indicators:
- Requests to known malicious domains hosting exploit code
- Unusual outbound connections following Chrome usage
SIEM Query:
source="chrome" AND (event_type="crash" OR process_name="chrome_renderer") AND message="*Skia*" OR "*heap overflow*"🔗 References
- https://chromereleases.googleblog.com/2021/10/stable-channel-update-for-desktop_19.html
- https://crbug.com/1246631
- https://www.debian.org/security/2022/dsa-5046
- https://chromereleases.googleblog.com/2021/10/stable-channel-update-for-desktop_19.html
- https://crbug.com/1246631
- https://www.debian.org/security/2022/dsa-5046
