CVE-2026-6773: Mozilla Firefox DOS Vulnerability

CVE-2026-6773 Overview

CVE-2026-6773 is a denial-of-service vulnerability caused by an integer overflow in the Graphics: WebGPU component of Mozilla Firefox and Thunderbird. This flaw allows remote attackers to trigger an integer overflow condition by sending specially crafted WebGPU requests, resulting in application crashes and service disruption. The vulnerability was addressed in Firefox 150 and Thunderbird 150.

Critical Impact

Remote attackers can exploit this integer overflow to cause denial-of-service conditions in affected Mozilla applications, disrupting user productivity and potentially affecting enterprise environments where these browsers are deployed at scale.

Affected Products

• Mozilla Firefox (versions prior to 150)
• Mozilla Thunderbird (versions prior to 150)

Discovery Timeline

• 2026-04-21 - CVE-2026-6773 published to NVD
• 2026-04-22 - Last updated in NVD database

Technical Details for CVE-2026-6773

Vulnerability Analysis

This vulnerability exists in the WebGPU graphics component of Mozilla Firefox and Thunderbird. WebGPU is a modern graphics API that provides advanced GPU capabilities for web applications. The integer overflow (CWE-190) occurs when the component processes certain input values that exceed the maximum integer boundary, causing the value to wrap around and produce unexpected behavior.

The vulnerability is network-exploitable without requiring any authentication or user interaction. An attacker can craft malicious WebGPU content that, when processed by the browser, triggers the integer overflow condition. While the vulnerability does not lead to information disclosure or code execution, it results in complete loss of availability for the affected application.

Root Cause

The root cause is an integer overflow condition (CWE-190) in the WebGPU graphics processing code. When arithmetic operations on integer values exceed the maximum storage capacity, the result wraps around to a small or negative number. In this case, the overflow leads to memory corruption or invalid state that causes the application to crash.

Attack Vector

The attack vector is network-based, allowing remote exploitation. An attacker can host malicious content on a website or inject malicious WebGPU code into a compromised page. When a victim visits the malicious page using a vulnerable version of Firefox or Thunderbird (for HTML email rendering), the browser processes the WebGPU content, triggering the integer overflow and causing a denial-of-service condition.

The vulnerability can be exploited through specially crafted WebGPU shader code or buffer operations that cause integer values to overflow during graphics processing. The attack requires no special privileges and no user interaction beyond visiting the malicious content.

Detection Methods for CVE-2026-6773

Indicators of Compromise

• Unexpected Firefox or Thunderbird process crashes with WebGPU-related error signatures
• Repeated application restarts triggered by visiting specific web pages
• Browser crash dumps indicating integer overflow in graphics subsystem components
• User reports of consistent denial-of-service when accessing certain websites

Detection Strategies

• Monitor for abnormal crash patterns in Firefox and Thunderbird processes across the enterprise
• Implement endpoint detection rules to identify WebGPU-related crash signatures
• Review application event logs for repeated crash events from the same source URL
• Deploy browser telemetry monitoring to detect exploitation attempts

Monitoring Recommendations

• Enable crash reporting and centralize browser crash telemetry for analysis
• Monitor network traffic for known malicious domains hosting WebGPU exploitation content
• Implement anomaly detection for unusual patterns of browser process terminations
• Track browser version deployments to ensure vulnerable versions are identified

How to Mitigate CVE-2026-6773

Immediate Actions Required

• Update Mozilla Firefox to version 150 or later immediately
• Update Mozilla Thunderbird to version 150 or later immediately
• Consider temporarily disabling WebGPU functionality via browser configuration if immediate updates are not possible
• Review enterprise browser deployment policies to prioritize security updates

Patch Information

Mozilla has released security patches addressing this vulnerability. The fix is included in Firefox 150 and Thunderbird 150. Organizations should apply these updates as soon as possible.

For detailed patch information, refer to the official Mozilla Security Advisories:

• Mozilla Security Advisory MFSA-2026-30
• Mozilla Security Advisory MFSA-2026-33

Additional technical details are available in Mozilla Bug Report #2015959.

Workarounds

• Disable WebGPU functionality in Firefox by navigating to about:config and setting dom.webgpu.enabled to false
• Implement content security policies to restrict WebGPU access on untrusted sites
• Use browser isolation technologies to contain potential exploitation attempts
• Block access to known malicious domains at the network perimeter

# Firefox configuration to disable WebGPU (about:config)
# Set this preference to false to disable WebGPU functionality
user_pref("dom.webgpu.enabled", false);