CVE-2021-30625 – This is a use-after-free vulnerability in Chrom... (How to Fix)

Q: What is the severity of CVE-2021-30625?

CVE-2021-30625 has a CVSS score of 8.8 (HIGH). This is a use-after-free vulnerability in Chrome's Selection API that allows remote attackers to potentially exploit heap corruption. Attackers can trigger this by convincing users to visit a malicious website with crafted HTML. All users running vulnerable Chrome versions are affected.

📋 TL;DR

This is a use-after-free vulnerability in Chrome's Selection API that allows remote attackers to potentially exploit heap corruption. Attackers can trigger this by convincing users to visit a malicious website with crafted HTML. All users running vulnerable Chrome versions are affected.

💻 Affected Systems

Products:

Google Chrome

Versions: All versions prior to 93.0.4577.82

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

Default Config Vulnerable: ⚠️ Yes

Notes: All Chrome installations with vulnerable versions are affected regardless of configuration

📦 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...

Learn more about Chrome →

Fedora by Fedoraproject

View all CVEs affecting Fedora →

Fedora by Fedoraproject

View all CVEs affecting Fedora →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to full system compromise, data theft, or malware installation

🟠

Likely Case

Browser crash, denial of service, or limited information disclosure

🟢

If Mitigated

No impact if Chrome is updated to patched version

🌐 Internet-Facing: HIGH - Exploitable via malicious websites without user interaction beyond visiting the site

🏢 Internal Only: MEDIUM - Requires user to visit malicious internal site or external site through browser

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires heap manipulation and memory corruption techniques but has been demonstrated in proof-of-concept

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 93.0.4577.82 and later

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

Restart Required: Yes

Instructions:

1. Open Chrome browser 2. Click 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 JavaScript

all

Prevents exploitation by disabling JavaScript execution in Chrome

Use Site Isolation

all

Enable site isolation to limit impact of successful exploitation

🧯 If You Can't Patch

Restrict browser usage to trusted websites only
Implement web filtering to block malicious sites

🔍 How to Verify

Check if Vulnerable:

Check Chrome version in Settings → About Chrome. If version is below 93.0.4577.82, system is vulnerable.

Check Version:

google-chrome --version (Linux) or navigate to chrome://version/

Verify Fix Applied:

Verify Chrome version is 93.0.4577.82 or higher after update

📡 Detection & Monitoring

Log Indicators:

Chrome crash reports
Unexpected process termination
Memory access violation logs

Network Indicators:

Requests to known malicious domains hosting exploit code
Unusual outbound connections after visiting websites

SIEM Query:

source="chrome" AND (event_type="crash" OR message="*Selection API*" OR message="*use-after-free*")

📊 Metadata

CVE ID: CVE-2021-30625

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: October 8, 2021

Last Updated: November 21, 2024

🔗 References

https://chromereleases.googleblog.com/2021/09/stable-channel-update-for-desktop.html Release Notes,Vendor Advisory
https://crbug.com/1237533 Permissions Required,Vendor Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4DDW7HAHTS3SDVXBQUY4SURELO5D4X7R/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PM7MOYYHJSWLIFZ4TPJTD7MSA3HSSLV2/
https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1352 Exploit,Third Party Advisory
https://chromereleases.googleblog.com/2021/09/stable-channel-update-for-desktop.html Release Notes,Vendor Advisory
https://crbug.com/1237533 Permissions Required,Vendor Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4DDW7HAHTS3SDVXBQUY4SURELO5D4X7R/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PM7MOYYHJSWLIFZ4TPJTD7MSA3HSSLV2/
https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1352 Exploit,Third Party Advisory

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2021-30625, you might also want to check these: