CVE-2020-6465: Google Chrome Use-After-Free Vulnerability

CVE-2020-6465 Overview

CVE-2020-6465 is a critical use-after-free vulnerability in the reader mode component of Google Chrome on Android. This memory corruption flaw allows a remote attacker who has already compromised the renderer process to potentially escape the browser sandbox through a specially crafted HTML page. Successful exploitation could grant an attacker elevated privileges beyond the sandboxed renderer environment, enabling further system compromise.

Critical Impact

A remote attacker who has compromised the renderer process can potentially perform a sandbox escape, breaking Chrome's security boundaries and gaining access to system resources normally protected by the sandbox.

Affected Products

• Google Chrome prior to version 83.0.4103.61
• openSUSE Backports SLE 15.0 SP1
• Debian Linux 9.0 and 10.0
• Fedora 31 and 32
• openSUSE Leap 15.1

Discovery Timeline

• May 21, 2020 - CVE-2020-6465 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2020-6465

Vulnerability Analysis

This vulnerability exists within Chrome's reader mode functionality, which provides a simplified, distraction-free view of web content. The use-after-free condition occurs when the reader mode component references memory that has already been deallocated. In browser security architecture, the renderer process operates within a sandbox designed to contain compromised code. However, this vulnerability provides a pathway for an attacker who has already gained code execution within the renderer to escape the sandbox boundaries.

The attack requires user interaction—specifically, a victim must navigate to a malicious HTML page. Once the renderer is compromised (potentially through a separate vulnerability), this use-after-free can be leveraged to execute arbitrary code outside the sandbox, gaining access to system resources and potentially achieving full system compromise.

Root Cause

The vulnerability is classified as CWE-416 (Use After Free), indicating improper memory management in the reader mode component. The code continues to reference a memory location after it has been freed, creating a condition where the attacker can potentially control the contents of that memory region. When the freed memory is subsequently accessed, the attacker-controlled data can hijack program execution flow.

Attack Vector

The attack is network-based, requiring the victim to visit a malicious webpage. The exploitation chain typically involves:

1. Initial renderer compromise through a separate vulnerability or attack vector
2. Triggering the reader mode use-after-free condition through crafted HTML content
3. Manipulating the freed memory to achieve controlled code execution
4. Escaping the renderer sandbox to gain broader system access

The vulnerability's sandbox escape capability makes it particularly dangerous, as Chrome's multi-process architecture normally isolates compromised renderers from sensitive system resources.

Detection Methods for CVE-2020-6465

Indicators of Compromise

• Unusual Chrome renderer process behavior, including unexpected memory access patterns or crashes
• Attempts to access system resources outside normal renderer sandbox permissions
• Chrome crash reports indicating use-after-free conditions in reader mode components
• Network requests to known malicious pages hosting exploit code

Detection Strategies

• Monitor for Chrome process crashes with memory corruption signatures, particularly in reader mode functionality
• Implement browser version auditing to identify systems running vulnerable Chrome versions prior to 83.0.4103.61
• Deploy endpoint detection solutions capable of identifying sandbox escape attempts
• Analyze browser telemetry for anomalous reader mode activation patterns

Monitoring Recommendations

• Enable Chrome crash reporting and monitor for patterns indicative of exploitation attempts
• Implement network monitoring to detect connections to known malicious infrastructure
• Deploy endpoint detection and response (EDR) solutions to identify post-exploitation activity
• Review system logs for evidence of processes spawned from Chrome with elevated privileges

How to Mitigate CVE-2020-6465

Immediate Actions Required

• Update Google Chrome to version 83.0.4103.61 or later immediately
• Apply security updates for affected Linux distributions (Debian, Fedora, openSUSE)
• Audit deployed Chrome versions across the organization to identify vulnerable instances
• Consider implementing browser isolation solutions for high-risk users

Patch Information

Google addressed this vulnerability in the Chrome 83.0.4103.61 stable channel release on May 19, 2020. The fix resolves the improper memory handling in the reader mode component. Security updates are also available from downstream Linux distributions:

• Chrome Stable Channel Update - Official Google release notes
• Debian Security Advisory DSA-4714
• Gentoo GLSA 202006-02

Workarounds

• If immediate patching is not possible, consider temporarily disabling or restricting access to reader mode functionality
• Implement network-level filtering to block access to known malicious domains
• Deploy browser isolation technology to contain potential exploitation attempts
• Restrict browsing to trusted sites on systems where Chrome cannot be immediately updated

# Verify Chrome version on Linux systems
google-chrome --version

# For enterprise deployments, enforce minimum version via policy
# Example: Set minimum required version in Chrome enterprise policy
# MinimumChromeVersionEnforced: "83.0.4103.61"