CVE-2023-6707: Google Chrome Use After Free Vulnerability

CVE-2023-6707 Overview

CVE-2023-6707 is a Use After Free vulnerability affecting the CSS component in Google Chrome prior to version 120.0.6099.109. This memory corruption flaw allows a remote attacker to potentially exploit heap corruption through a specially crafted HTML page. The vulnerability stems from improper memory management in Chrome's CSS rendering engine, where memory is accessed after it has been freed, leading to undefined behavior and potential arbitrary code execution.

Critical Impact

Successful exploitation of this Use After Free vulnerability could allow remote attackers to execute arbitrary code, compromise user systems, or cause browser crashes through heap corruption when victims visit malicious web pages.

Affected Products

• Google Chrome versions prior to 120.0.6099.109
• Chromium-based browsers using affected versions
• Fedora Linux packages containing vulnerable Chrome versions

Discovery Timeline

• 2023-12-14 - CVE-2023-6707 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-6707

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a common memory corruption issue that occurs when a program continues to use a pointer after the memory it references has been deallocated. In the context of Google Chrome's CSS engine, this vulnerability allows attackers to manipulate the browser's memory state through carefully crafted HTML and CSS content.

The attack requires user interaction—specifically, the victim must navigate to a malicious web page controlled by the attacker. Once the page loads, the crafted HTML content triggers the Use After Free condition in the CSS parsing or rendering code, potentially allowing the attacker to overwrite critical memory structures and gain control of program execution.

Root Cause

The root cause of CVE-2023-6707 lies in improper lifecycle management of memory objects within Chrome's CSS processing component. When certain CSS operations are performed, the browser may free a memory object while retaining a dangling pointer to that memory location. Subsequent access through this stale pointer leads to the Use After Free condition.

This type of vulnerability typically arises from complex object relationships in rendering engines, where multiple components may hold references to shared objects without proper synchronization of their lifetimes. The CSS engine's handling of style recalculation or DOM manipulation appears to contain a path where these references become desynchronized.

Attack Vector

The attack vector for CVE-2023-6707 is network-based and requires user interaction. An attacker would need to:

1. Create a malicious web page containing specially crafted HTML and CSS content designed to trigger the Use After Free condition
2. Lure a victim to visit the malicious page through phishing, malvertising, or compromising a legitimate website
3. Upon page load, the crafted content triggers the vulnerable code path in Chrome's CSS engine
4. The heap corruption resulting from the Use After Free can be leveraged to achieve arbitrary code execution or cause denial of service

The vulnerability does not require any special privileges and can be exploited against any user running an unpatched version of Chrome. For detailed technical information, refer to the Chrome Bug Report #1504036.

Detection Methods for CVE-2023-6707

Indicators of Compromise

• Unexpected browser crashes or memory corruption errors during normal web browsing
• Chrome processes consuming abnormally high memory before crashing
• Suspicious network connections originating from Chrome to unknown malicious domains
• Evidence of heap spray patterns or shellcode execution in Chrome process memory

Detection Strategies

• Monitor Chrome browser version across endpoints and flag any installations below 120.0.6099.109
• Deploy endpoint detection rules to identify heap corruption patterns associated with Use After Free exploits
• Implement network monitoring to detect access to known malicious domains hosting exploit kits
• Use browser isolation technologies to contain potential exploitation attempts

Monitoring Recommendations

• Enable Chrome's built-in crash reporting to identify potential exploitation attempts
• Monitor endpoint telemetry for unusual Chrome process behavior including unexpected child processes
• Track browser update compliance across the organization to ensure timely patching
• Review web proxy logs for connections to suspicious or newly registered domains

How to Mitigate CVE-2023-6707

Immediate Actions Required

• Update Google Chrome to version 120.0.6099.109 or later immediately
• Enable automatic updates in Chrome to receive future security patches promptly
• Consider using browser isolation for high-risk users until patching is complete
• Educate users about the risks of visiting untrusted websites

Patch Information

Google has released a security update addressing this vulnerability in Chrome version 120.0.6099.109. The fix resolves the improper memory management in the CSS component that allowed the Use After Free condition. Organizations should prioritize updating all Chrome installations to this version or later.

For official patch details, see the Google Chrome Update Bulletin. Linux distributions have also released updates—refer to the Gentoo GLSA 202401-34 and Fedora Package Announcement for distribution-specific guidance.

Workarounds

• Restrict access to untrusted websites using web filtering or proxy solutions until patching is complete
• Consider disabling JavaScript on untrusted sites as a temporary measure to reduce attack surface
• Use browser sandboxing technologies to limit the impact of potential exploitation
• Deploy network-level protections to block known malicious domains

# Verify Chrome version on Linux/macOS
google-chrome --version
# Expected output should show 120.0.6099.109 or higher

# Force Chrome update check
# Navigate to chrome://settings/help in the browser
# Or use enterprise deployment tools to push updates