CVE-2021-30548 – This is a use-after-free vulnerability in Chrom... (How to Fix)

Q: What is the severity of CVE-2021-30548?

CVE-2021-30548 has a CVSS score of 8.8 (HIGH). This is a use-after-free vulnerability in Chrome's Loader component that allows remote attackers to potentially exploit heap corruption. Attackers can trigger this by tricking users into visiting a malicious HTML page, potentially leading to arbitrary code execution. All Chrome users on versions prior to 91.0.4472.101 are affected.

📋 TL;DR

This is a use-after-free vulnerability in Chrome's Loader component that allows remote attackers to potentially exploit heap corruption. Attackers can trigger this by tricking users into visiting a malicious HTML page, potentially leading to arbitrary code execution. All Chrome users on versions prior to 91.0.4472.101 are affected.

💻 Affected Systems

Products:

Google Chrome

Versions: All versions prior to 91.0.4472.101

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

Default Config Vulnerable: ⚠️ Yes

Notes: All standard Chrome installations are vulnerable. Extensions or security settings do not mitigate this vulnerability.

📦 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, data theft, or ransomware deployment.

🟠

Likely Case

Browser crash (denial of service) or limited code execution within the browser sandbox, potentially enabling further exploitation.

🟢

If Mitigated

No impact if Chrome is fully patched or if exploit attempts are blocked by security controls.

🌐 Internet-Facing: HIGH

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires user interaction (visiting malicious page) but no authentication. Heap corruption vulnerabilities are often weaponized in browser exploit chains.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 91.0.4472.101 and later

Vendor Advisory: https://chromereleases.googleblog.com/2021/06/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 updates and install version 91.0.4472.101 or later. 4. Click 'Relaunch' to restart Chrome.

🔧 Temporary Workarounds

Disable JavaScript

all

Prevents execution of malicious JavaScript that could trigger the vulnerability

chrome://settings/content/javascript → Block

Use Site Isolation

all

Enables Chrome's Site Isolation feature to limit impact of renderer process compromises

chrome://flags/#enable-site-per-process → Enable

🧯 If You Can't Patch

Use alternative browsers until Chrome can be updated
Implement network filtering to block known malicious sites and HTML content

🔍 How to Verify

Check if Vulnerable:

Check Chrome version: If version is below 91.0.4472.101, system is vulnerable.

Check Version:

chrome://version

Verify Fix Applied:

Confirm Chrome version is 91.0.4472.101 or higher after update.

📡 Detection & Monitoring

Log Indicators:

Chrome crash reports with memory corruption signatures
Unexpected Chrome process termination

Network Indicators:

Requests to suspicious domains serving HTML content
Unusual outbound connections after visiting web pages

SIEM Query:

source="chrome" AND (event_type="crash" OR memory_corruption="true")

📊 Metadata

CVE ID: CVE-2021-30548

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: June 15, 2021

Last Updated: November 21, 2024

🔗 References

https://chromereleases.googleblog.com/2021/06/stable-channel-update-for-desktop.html Release Notes,Vendor Advisory
https://crbug.com/1210487 Issue Tracking,Third Party Advisory
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 Third Party Advisory
https://chromereleases.googleblog.com/2021/06/stable-channel-update-for-desktop.html Release Notes,Vendor Advisory
https://crbug.com/1210487 Issue Tracking,Third Party Advisory
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 Third Party Advisory

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