CVE-2025-13021: Mozilla Firefox WebGPU Boundary Flaw

CVE-2025-13021 Overview

CVE-2025-13021 is a critical boundary condition vulnerability in the Graphics: WebGPU component of Mozilla Firefox and Thunderbird. The flaw stems from incorrect boundary conditions that can be exploited remotely without requiring user interaction or authentication. This vulnerability affects Firefox versions prior to 145 and Thunderbird versions prior to 145.

Critical Impact

This vulnerability allows remote attackers to potentially achieve full system compromise through the browser's WebGPU graphics processing component. The network-accessible attack vector combined with no required privileges makes this a high-priority security concern for all Firefox and Thunderbird users.

Affected Products

• Mozilla Firefox versions prior to 145
• Mozilla Thunderbird versions prior to 145
• Systems using WebGPU graphics rendering functionality

Discovery Timeline

• 2025-11-11 - CVE-2025-13021 published to NVD
• 2025-11-19 - Last updated in NVD database

Technical Details for CVE-2025-13021

Vulnerability Analysis

This vulnerability is classified under CWE-703 (Improper Check or Handling of Exceptional Conditions), indicating that the WebGPU component fails to properly validate boundary conditions during graphics processing operations. The WebGPU API provides low-level access to GPU capabilities for web applications, and improper boundary checking in this component can lead to memory corruption or unauthorized memory access.

The flaw exists in how the WebGPU implementation handles boundary conditions during graphics rendering operations. When malformed or specially crafted graphics data is processed, the component fails to properly validate boundaries, potentially allowing attackers to read or write memory outside intended buffers.

Root Cause

The root cause lies in insufficient validation of boundary conditions within the WebGPU graphics processing pipeline. The component does not adequately verify that data operations stay within allocated memory regions, leading to potential out-of-bounds access scenarios. This type of boundary condition error can occur when processing untrusted graphics content from web pages.

Attack Vector

The vulnerability is exploitable over the network with low attack complexity. An attacker can craft a malicious web page containing specially designed WebGPU content that triggers the boundary condition error when a victim visits the page. No authentication or user interaction beyond visiting the malicious page is required for exploitation.

The attack scenario involves hosting malicious content on a web server or injecting it into compromised websites. When a Firefox or Thunderbird user processes content containing the crafted WebGPU instructions, the boundary condition vulnerability is triggered, potentially leading to arbitrary code execution or information disclosure.

Detection Methods for CVE-2025-13021

Indicators of Compromise

• Unexpected browser crashes or instability when rendering web pages with WebGPU content
• Unusual memory consumption patterns in Firefox or Thunderbird processes
• Suspicious WebGPU API calls originating from untrusted web content
• Browser process spawning unexpected child processes

Detection Strategies

• Monitor browser process behavior for anomalous memory access patterns
• Implement network-level inspection for known WebGPU exploitation patterns
• Deploy endpoint detection rules that flag unusual graphics subsystem activity
• Review browser crash reports for signatures matching boundary condition violations

Monitoring Recommendations

• Enable enhanced logging for browser graphics subsystem operations
• Monitor for unexpected browser process behavior following web page visits
• Track WebGPU API usage patterns across the environment
• Implement browser telemetry collection to identify potential exploitation attempts

How to Mitigate CVE-2025-13021

Immediate Actions Required

• Update Mozilla Firefox to version 145 or later immediately
• Update Mozilla Thunderbird to version 145 or later immediately
• Consider temporarily disabling WebGPU functionality in environments where updates cannot be immediately applied
• Review browser configurations across the enterprise for affected versions

Patch Information

Mozilla has released security patches addressing this vulnerability in Firefox 145 and Thunderbird 145. Organizations should prioritize deploying these updates across all systems. Detailed patch information is available in the Mozilla Security Advisory MFSA-2025-87 and Mozilla Security Advisory MFSA-2025-90. Additional technical details can be found in Mozilla Bug Report #1986431.

Workarounds

• Disable WebGPU by setting dom.webgpu.enabled to false in about:config as a temporary mitigation
• Implement content filtering to block known malicious domains serving WebGPU exploits
• Use browser isolation solutions to limit exposure of critical systems to untrusted web content
• Consider using alternative browsers temporarily until patches can be deployed

# Firefox configuration to disable WebGPU (temporary workaround)
# Navigate to about:config and set:
# dom.webgpu.enabled = false

# For enterprise deployments, use policies.json:
# {
#   "policies": {
#     "Preferences": {
#       "dom.webgpu.enabled": false
#     }
#   }
# }