CVE-2021-30535
📋 TL;DR
This vulnerability is a double-free memory corruption flaw in Chrome's ICU library that allows remote attackers to potentially execute arbitrary code or cause denial of service. It affects Google Chrome users on all platforms who visit malicious websites. The vulnerability can be triggered through a crafted HTML page without user interaction.
💻 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...
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⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment.
Likely Case
Browser crash (denial of service) or limited code execution within sandboxed Chrome process.
If Mitigated
Browser crash only, with Chrome's sandbox preventing system-level compromise.
🎯 Exploit Status
Exploitation requires bypassing Chrome's sandbox and ASLR for full RCE. Basic DoS is easier to achieve.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 91.0.4472.77
Vendor Advisory: https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop_25.html
Restart Required: Yes
Instructions:
1. Open Chrome 2. Click menu (three dots) → Help → About Google Chrome 3. Chrome will automatically check for and install update 4. Click 'Relaunch' to restart Chrome
🔧 Temporary Workarounds
Disable JavaScript
allPrevents exploitation by disabling JavaScript execution in Chrome
chrome://settings/content/javascript → Toggle to 'Blocked'
Use Site Isolation
allEnhances Chrome's site isolation to limit impact
chrome://flags/#enable-site-per-process → Enable
🧯 If You Can't Patch
- Use alternative browsers until Chrome can be updated
- Implement network filtering to block known malicious sites
🔍 How to Verify
Check if Vulnerable:
Check Chrome version: chrome://version/ - if version is below 91.0.4472.77, system is vulnerableCheck Version:
google-chrome --version (Linux) or check chrome://version/ (all platforms)Verify Fix Applied:
Confirm Chrome version is 91.0.4472.77 or higher via chrome://version/📡 Detection & Monitoring
Log Indicators:
- Chrome crash reports with memory corruption errors
- Unexpected Chrome process termination
Network Indicators:
- Requests to known malicious domains serving exploit code
- Unusual outbound connections after visiting suspicious sites
SIEM Query:
source="chrome" AND (event_type="crash" OR message="*double free*" OR message="*heap corruption*")🔗 References
- https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop_25.html
- https://crbug.com/1194899
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ETMZL6IHCTCTREEL434BQ4THQ7EOHJ43/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PAT6EOXVQFE6JFMFQF4IKAOUQSHMHL54/
- https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop_25.html
- https://crbug.com/1194899
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ETMZL6IHCTCTREEL434BQ4THQ7EOHJ43/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PAT6EOXVQFE6JFMFQF4IKAOUQSHMHL54/
