CVE-2021-30606 – CVE-2021-30606 is a use-after-free vulnerabilit... (How to Fix)

Q: What is the severity of CVE-2021-30606?

CVE-2021-30606 has a CVSS score of 8.8 (HIGH). CVE-2021-30606 is a use-after-free vulnerability in Chromium's Blink rendering engine that allows remote attackers to execute arbitrary code or cause denial of service via crafted web content. This affects all Chromium-based browsers including Google Chrome, Microsoft Edge, and other derivatives. Users who visit malicious websites or view crafted content are vulnerable.

📋 TL;DR

CVE-2021-30606 is a use-after-free vulnerability in Chromium's Blink rendering engine that allows remote attackers to execute arbitrary code or cause denial of service via crafted web content. This affects all Chromium-based browsers including Google Chrome, Microsoft Edge, and other derivatives. Users who visit malicious websites or view crafted content are vulnerable.

💻 Affected Systems

Products:

Google Chrome
Microsoft Edge
Chromium-based browsers

Versions: Chromium versions before 93.0.4577.82

Operating Systems: Windows, Linux, macOS, Android

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 leading to complete system compromise, data theft, or ransomware deployment.

🟠

Likely Case

Browser crash (denial of service) or limited code execution within browser sandbox.

🟢

If Mitigated

Browser sandboxing may contain exploitation, but privilege escalation is possible.

🌐 Internet-Facing: HIGH - Exploitable via visiting malicious websites or viewing crafted content.

🏢 Internal Only: MEDIUM - Requires user interaction with malicious content, which could be delivered internally.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Use-after-free vulnerabilities in browser engines are commonly exploited in the wild.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Chrome 93.0.4577.82 and later, Edge 93.0.961.47 and later

Vendor Advisory: https://chromereleases.googleblog.com/2021/09/stable-channel-update-for-desktop.html

Restart Required: Yes

Instructions:

1. Open Chrome/Edge browser 2. Click menu → Help → About Google Chrome/About Microsoft Edge 3. Browser will automatically check for and install updates 4. Click Relaunch to restart browser

🔧 Temporary Workarounds

Disable JavaScript

all

Temporarily disable JavaScript to prevent exploitation (breaks most websites)

chrome://settings/content/javascript → Block

Use browser sandboxing

all

Ensure browser sandbox is enabled and properly configured

🧯 If You Can't Patch

Restrict browser usage to trusted websites only
Implement network filtering to block malicious content delivery

🔍 How to Verify

Check if Vulnerable:

Check browser version: Chrome/Edge → Help → About

Check Version:

chrome://version or edge://version

Verify Fix Applied:

Verify browser version is 93.0.4577.82 or higher for Chrome, 93.0.961.47 or higher for Edge

📡 Detection & Monitoring

Log Indicators:

Browser crash reports
Unusual process termination
Memory access violations

Network Indicators:

Requests to known exploit domains
Unusual JavaScript execution patterns

SIEM Query:

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

📊 Metadata

CVE ID: CVE-2021-30606

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

CWE: CWE-416

Published: September 3, 2021

Last Updated: November 21, 2024

🔗 References

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🔗 Related Vulnerabilities

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