CVE-2021-30608 – CVE-2021-30608 is a use-after-free vulnerabilit... (How to Fix)

Q: What is the severity of CVE-2021-30608?

CVE-2021-30608 has a CVSS score of 8.8 (HIGH). CVE-2021-30608 is a use-after-free vulnerability in Chromium's Web Share API that allows remote attackers to execute arbitrary code or cause a denial of service via a crafted HTML page. This affects all Chromium-based browsers including Google Chrome, Microsoft Edge, and other derivatives. Users who visit malicious websites with vulnerable browser versions are at risk.

📋 TL;DR

CVE-2021-30608 is a use-after-free vulnerability in Chromium's Web Share API that allows remote attackers to execute arbitrary code or cause a denial of service via a crafted HTML page. This affects all Chromium-based browsers including Google Chrome, Microsoft Edge, and other derivatives. Users who visit malicious websites with vulnerable browser versions are at risk.

💻 Affected Systems

Products:

Google Chrome
Microsoft Edge
Chromium-based browsers

Versions: Chrome versions before 93.0.4577.63, Edge versions before 93.0.961.38

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

Default Config Vulnerable: ⚠️ Yes

Notes: All standard installations are vulnerable; requires JavaScript execution.

📦 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 in browser sandbox.

🟢

If Mitigated

Browser crash with no further impact if sandbox holds, or blocked by security controls.

🌐 Internet-Facing: HIGH - Exploitable via visiting malicious websites.

🏢 Internal Only: MEDIUM - Requires user interaction with malicious content.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires user to visit malicious website; no authentication needed.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Chrome 93.0.4577.63, Edge 93.0.961.38

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. Browser will automatically check for and apply updates. 4. Restart browser when prompted.

🔧 Temporary Workarounds

Disable JavaScript

all

Prevents exploitation by blocking JavaScript execution.

Use browser extensions to block scripts

all

Extensions like NoScript or uBlock Origin can block malicious scripts.

🧯 If You Can't Patch

Restrict browser usage to trusted websites only.
Implement network filtering to block known malicious domains.

🔍 How to Verify

Check if Vulnerable:

Check browser version in settings; if below Chrome 93.0.4577.63 or Edge 93.0.961.38, it's vulnerable.

Check Version:

chrome://version/ or edge://version/

Verify Fix Applied:

Confirm browser version is Chrome 93.0.4577.63+ or Edge 93.0.961.38+ after update.

📡 Detection & Monitoring

Log Indicators:

Browser crash logs with memory access violations
Unexpected process termination

Network Indicators:

Requests to known malicious domains hosting exploit code

SIEM Query:

source="browser_logs" AND (event="crash" OR event="access_violation")

📊 Metadata

CVE ID: CVE-2021-30608

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

📤 Share & Export

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🔗 Related Vulnerabilities

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