CVE-2021-21198
📋 TL;DR
This vulnerability allows a remote attacker who has already compromised Chrome's renderer process to perform an out-of-bounds read in IPC (Inter-Process Communication) and potentially escape the browser's sandbox. This could lead to full system compromise. All users running Google Chrome versions prior to 89.0.4389.114 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...
Learn more about Chrome →Fedora by Fedoraproject
Fedora by Fedoraproject
Fedora by Fedoraproject
⚠️ Risk & Real-World Impact
Worst Case
Complete sandbox escape leading to arbitrary code execution with system-level privileges, potentially compromising the entire host system.
Likely Case
Successful sandbox escape allowing attacker to execute arbitrary code outside browser sandbox, but requiring prior renderer process compromise.
If Mitigated
Attack fails due to updated Chrome version or other security controls, limiting impact to renderer process only.
🎯 Exploit Status
Exploit requires chaining with another vulnerability to first compromise renderer process. Public PoC available via Packet Storm.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 89.0.4389.114
Vendor Advisory: https://chromereleases.googleblog.com/2021/03/stable-channel-update-for-desktop_30.html
Restart Required: Yes
Instructions:
1. Open Chrome. 2. Click three-dot menu → Help → About Google Chrome. 3. Chrome will automatically check for and install update. 4. Click 'Relaunch' to restart Chrome with updated version.
🔧 Temporary Workarounds
Disable JavaScript
allPrevents execution of malicious JavaScript that could trigger the vulnerability
chrome://settings/content/javascript → Block
Use Site Isolation
allEnforces process separation between websites to limit impact
chrome://flags/#site-isolation-trial-opt-out → Disabled
🧯 If You Can't Patch
- Restrict access to untrusted websites using browser extensions or network filtering
- Implement application whitelisting to prevent unauthorized Chrome execution
🔍 How to Verify
Check if Vulnerable:
Check Chrome version: If version is less than 89.0.4389.114, system is vulnerable.Check Version:
google-chrome --version (Linux) or chrome://version (all platforms)Verify Fix Applied:
Confirm Chrome version is 89.0.4389.114 or later after update.📡 Detection & Monitoring
Log Indicators:
- Chrome crash reports with IPC-related errors
- Unexpected Chrome child process termination
Network Indicators:
- Requests to known exploit hosting domains
- Unusual outbound connections from Chrome processes
SIEM Query:
process_name:"chrome.exe" AND (event_id:1000 OR event_id:1001) AND message:"ipc" OR "sandbox"🔗 References
- http://packetstormsecurity.com/files/162973/Chrome-Legacy-ipc-Message-Passed-Via-Shared-Memory.html
- https://chromereleases.googleblog.com/2021/03/stable-channel-update-for-desktop_30.html
- https://crbug.com/1184399
- 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/162973/Chrome-Legacy-ipc-Message-Passed-Via-Shared-Memory.html
- https://chromereleases.googleblog.com/2021/03/stable-channel-update-for-desktop_30.html
- https://crbug.com/1184399
- 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
