CVE-2021-21119
📋 TL;DR
This is a use-after-free vulnerability in Chrome's media component that allows a remote attacker who has already compromised the renderer process to potentially exploit heap corruption. Attackers could execute arbitrary code or cause browser crashes by tricking users into visiting a malicious webpage. All Chrome users prior to version 88.0.4324.96 are affected.
💻 Affected Systems
- Google Chrome
- Microsoft Edge (Chromium-based)
📦 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 →Edge Chromium by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to full system compromise, data theft, or ransomware deployment.
Likely Case
Browser crash, denial of service, or limited code execution within sandbox constraints.
If Mitigated
No impact if Chrome is fully patched or if exploit attempts are blocked by security controls.
🎯 Exploit Status
Requires renderer process compromise first, then can be triggered via crafted HTML page.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 88.0.4324.96 and later
Vendor Advisory: https://chromereleases.googleblog.com/2021/01/stable-channel-update-for-desktop_19.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 updates. 4. Click 'Relaunch' to restart Chrome with the update.
🔧 Temporary Workarounds
Disable JavaScript
allPrevents execution of malicious JavaScript that could trigger the vulnerability.
chrome://settings/content/javascript → Block
Use Site Isolation
allEnhances sandboxing to limit impact of renderer compromise.
chrome://flags/#enable-site-per-process → Enable
🧯 If You Can't Patch
- Use alternative browser temporarily
- Implement network filtering to block malicious websites
🔍 How to Verify
Check if Vulnerable:
Check Chrome version in About Google Chrome page.Check Version:
google-chrome --versionVerify Fix Applied:
Confirm version is 88.0.4324.96 or higher.📡 Detection & Monitoring
Log Indicators:
- Chrome crash reports
- Renderer process termination logs
Network Indicators:
- Requests to known malicious domains hosting exploit code
SIEM Query:
source="chrome" AND (event="crash" OR event="renderer_killed")🔗 References
- https://chromereleases.googleblog.com/2021/01/stable-channel-update-for-desktop_19.html
- https://crbug.com/1160534
- https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-21119
- https://chromereleases.googleblog.com/2021/01/stable-channel-update-for-desktop_19.html
- https://crbug.com/1160534
- https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-21119
