CVE-2020-6492 Overview
CVE-2020-6492 is a Use After Free vulnerability in ANGLE (Almost Native Graphics Layer Engine), a critical graphics abstraction layer used by Google Chrome to translate OpenGL ES API calls to platform-specific graphics APIs. This memory corruption flaw in Chrome versions prior to 83.0.4103.97 allows a remote attacker to potentially escape the browser sandbox through a specially crafted HTML page, representing a severe threat to browser security.
Critical Impact
This vulnerability enables potential sandbox escape, allowing attackers to break out of Chrome's security isolation and execute arbitrary code on the underlying system with elevated privileges.
Affected Products
- Google Chrome versions prior to 83.0.4103.97
- All platforms running vulnerable Chrome versions (Windows, macOS, Linux)
- Chromium-based browsers using the affected ANGLE component
Discovery Timeline
- 2021-11-02 - CVE-2020-6492 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2020-6492
Vulnerability Analysis
The Use After Free vulnerability exists within ANGLE, Chrome's graphics translation layer that enables cross-platform WebGL and OpenGL ES rendering. When Chrome processes certain WebGL or graphics operations through ANGLE, the component may incorrectly handle memory lifecycle management, leading to a condition where memory is accessed after it has been freed.
This vulnerability is classified as CWE-416 (Use After Free), a dangerous 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 ANGLE, this flaw can be triggered remotely by visiting a malicious webpage containing crafted HTML and WebGL content.
The most severe aspect of this vulnerability is its potential to enable sandbox escape. Chrome's sandbox is designed to isolate web content from the underlying operating system, but exploitation of this Use After Free could allow an attacker to bypass these protections entirely.
Root Cause
The root cause lies in improper memory management within ANGLE's graphics processing code. When handling specific graphics operations, ANGLE fails to properly track the lifecycle of allocated memory objects. This results in dangling pointer references where freed memory can be reallocated and overwritten with attacker-controlled data.
When the dangling pointer is subsequently dereferenced, the attacker-controlled data is treated as legitimate program data, potentially allowing arbitrary code execution within the renderer process. Combined with the sandbox escape capability, this creates a critical attack chain.
Attack Vector
The attack is network-based and requires user interaction—specifically, a victim must navigate to or be redirected to a malicious webpage. The attacker crafts an HTML page containing WebGL or graphics operations that trigger the Use After Free condition in ANGLE.
The exploitation flow involves:
- Victim visits attacker-controlled webpage
- Malicious page executes crafted WebGL/graphics operations
- ANGLE processes the operations, triggering the Use After Free
- Attacker achieves code execution within the renderer process
- Sandbox escape allows full system compromise
The vulnerability can be triggered through crafted WebGL shader operations or specific ANGLE API calls that cause the graphics layer to mishandle memory allocation and deallocation sequences. Technical details are available in the Chromium Bug Report #1078375.
Detection Methods for CVE-2020-6492
Indicators of Compromise
- Unexpected Chrome renderer process crashes or restarts when visiting websites
- Anomalous WebGL rendering behavior or graphics errors in browser logs
- Unusual memory access patterns in Chrome's graphics subsystem
- Process spawning from Chrome that escapes the expected sandbox hierarchy
Detection Strategies
- Monitor for Chrome renderer crashes with ANGLE-related stack traces
- Implement browser version auditing to identify vulnerable Chrome installations (< 83.0.4103.97)
- Deploy endpoint detection to identify exploitation attempts targeting graphics APIs
- Analyze network traffic for suspicious HTML pages with complex WebGL operations
Monitoring Recommendations
- Enable Chrome crash reporting and analyze ANGLE-related crash dumps
- Monitor endpoint processes for unexpected child processes spawned from Chrome
- Implement web content inspection for known exploit patterns targeting ANGLE
- Track browser version compliance across the organization to ensure timely patching
How to Mitigate CVE-2020-6492
Immediate Actions Required
- Update Google Chrome to version 83.0.4103.97 or later immediately
- Enable automatic browser updates to receive security patches promptly
- Consider restricting WebGL on untrusted websites as a temporary measure
- Audit all Chromium-based browsers in the environment for the vulnerable component
Patch Information
Google has released a security update that addresses this vulnerability in Chrome version 83.0.4103.97. The patch corrects the memory management issues in ANGLE that allowed the Use After Free condition. Organizations should prioritize updating to the patched version.
For detailed information about the security update, refer to the Google Chrome Desktop Update announcement.
Workarounds
- Disable WebGL in Chrome via chrome://flags/#disable-webgl as a temporary mitigation
- Use browser isolation solutions to execute web content in sandboxed virtual environments
- Implement web filtering to block access to known malicious domains
- Consider using enterprise browser policies to restrict graphics API access on sensitive systems
# Chrome enterprise policy example to disable WebGL (Windows Registry)
# HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome
# WebGLAllowed REG_DWORD 0
# Linux/macOS managed preferences
# Set WebGLAllowed to false in Chrome managed policies JSON
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
