CVE-2021-30620 – CVE-2021-30620 is a high-severity vulnerability... (How to Fix)

Q: What is the severity of CVE-2021-30620?

CVE-2021-30620 has a CVSS score of 8.8 (HIGH). CVE-2021-30620 is a high-severity vulnerability in Chromium's Blink rendering engine where insufficient policy enforcement could allow attackers to bypass security restrictions. This affects all Chromium-based browsers including Google Chrome, Microsoft Edge, and other derivatives. Users who haven't updated their browsers are vulnerable to potential exploitation.

📋 TL;DR

CVE-2021-30620 is a high-severity vulnerability in Chromium's Blink rendering engine where insufficient policy enforcement could allow attackers to bypass security restrictions. This affects all Chromium-based browsers including Google Chrome, Microsoft Edge, and other derivatives. Users who haven't updated their browsers are vulnerable to potential exploitation.

💻 Affected Systems

Products:

Google Chrome
Microsoft Edge
Chromium-based browsers

Versions: Chromium versions prior to 93.0.4577.63

Operating Systems: Windows, Linux, macOS, Android, iOS

Default Config Vulnerable: ⚠️ Yes

Notes: All default configurations of affected browsers are vulnerable

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution allowing complete system compromise, data theft, or ransomware deployment

🟠

Likely Case

Arbitrary code execution in browser context leading to session hijacking, credential theft, or malware installation

🟢

If Mitigated

Limited impact with proper browser sandboxing and security controls in place

🌐 Internet-Facing: HIGH - Browser vulnerabilities are directly exposed to web content

🏢 Internal Only: MEDIUM - Still vulnerable to malicious internal sites or compromised internal resources

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires user to visit malicious website or open malicious content

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Chrome 93.0.4577.63 and later, Edge 93.0.961.38 and later

Vendor Advisory: https://chromereleases.googleblog.com/2021/08/stable-channel-update-for-desktop_31.html

Restart Required: Yes

Instructions:

1. Open browser settings 2. Navigate to About Chrome/Edge 3. Allow browser to check for updates 4. Restart browser when prompted

🔧 Temporary Workarounds

Disable JavaScript

all

Temporarily disable JavaScript to prevent exploitation

chrome://settings/content/javascript

Use Browser Sandboxing

all

Ensure browser runs in sandboxed mode

Verify Chrome/Edge is running with --no-sandbox flag NOT present

🧯 If You Can't Patch

Use alternative non-Chromium browser temporarily
Implement strict web filtering and block untrusted websites

🔍 How to Verify

Check if Vulnerable:

Check browser version in settings > About Chrome/Edge

Check Version:

chrome://version or edge://version

Verify Fix Applied:

Verify version is 93.0.4577.63 or higher for Chrome, 93.0.961.38 or higher for Edge

📡 Detection & Monitoring

Log Indicators:

Browser crash reports
Unusual process spawning from browser

Network Indicators:

Connections to suspicious domains after visiting specific sites

SIEM Query:

source="browser_logs" AND (event="crash" OR event="process_spawn") AND version<93

📊 Metadata

CVE ID: CVE-2021-30620

CVSS v3 Score: 8.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Published: September 3, 2021

Last Updated: November 21, 2024

🔗 References

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