CVE-2021-30518
📋 TL;DR
A heap buffer overflow vulnerability in Chrome's Reader Mode allows remote attackers to potentially exploit heap corruption via a crafted HTML page. This could lead to arbitrary code execution or browser crashes. All users of Google Chrome versions prior to 90.0.4430.212 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...
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⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with the same privileges as the Chrome process, potentially leading to full system compromise if Chrome is running with elevated privileges.
Likely Case
Browser crash (denial of service) or limited information disclosure from heap memory.
If Mitigated
No impact if Chrome is updated to patched version or if Reader Mode is disabled.
🎯 Exploit Status
Exploitation requires user interaction (visiting malicious page) but no authentication. Heap corruption vulnerabilities typically require precise memory manipulation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 90.0.4430.212 and later
Vendor Advisory: https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop.html
Restart Required: Yes
Instructions:
1. Open Chrome. 2. Click the 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 Reader Mode
allDisable the Reader Mode feature to prevent exploitation via this vector.
chrome://flags/#enable-reader-mode
Set to 'Disabled'
🧯 If You Can't Patch
- Use alternative browsers that are not vulnerable to this specific CVE
- Implement network filtering to block access to untrusted websites
🔍 How to Verify
Check if Vulnerable:
Check Chrome version: If version is less than 90.0.4430.212, system is vulnerable.Check Version:
google-chrome --version (Linux) or chrome://version (all platforms)Verify Fix Applied:
Verify Chrome version is 90.0.4430.212 or higher after update.📡 Detection & Monitoring
Log Indicators:
- Chrome crash reports with memory corruption errors
- Unexpected Chrome process termination
Network Indicators:
- HTTP requests to unusual domains followed by Chrome crashes
SIEM Query:
source="chrome" AND (event="crash" OR error="memory_corruption")🔗 References
- https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop.html
- https://crbug.com/1203590
- 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://security.gentoo.org/glsa/202107-06
- https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop.html
- https://crbug.com/1203590
- 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://security.gentoo.org/glsa/202107-06
