External risk intelligence

Firefox and Thunderbird Use-After-Free in Graphics WebGPU Component.

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-12293

A use-after-free vulnerability in the Graphics: WebGPU component of Firefox and Thunderbird could allow an attacker to execute arbitrary code or cause a denial of service. This could occur when processing web content, potentially impacting the integrity and availability of the affected application.

Use After Free

Mozilla Firefox

before 152.0.0

Halo Surface Signal

Very unlikely · external exposure

1Halo Surface Signal

This vulnerability affects web browser and email client software. These are client-side applications typically running on local end-user devices, not network-facing infrastructure, services, or servers. While they interact with internet content, they are not public-facing network services or gateways, making the vulnerable surface primarily client-side.

Horizon Alert

Summary of the vulnerability and why it matters

A critical use-after-free vulnerability has been identified in Mozilla's WebGPU component, affecting Firefox and Thunderbird. This issue could potentially allow for significant compromise if exploited. The primary concern is confirming relevance and exposure within your environment.

  • Software flaw allows unauthorized access and control.
  • Affects widely used browsing and email applications.
  • Confirm if your Mozilla software is updated.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by directing a user to a malicious webpage or sending a specially crafted email. The vulnerability exists in the Graphics: WebGPU component, which, when triggered, could allow an attacker to execute arbitrary code or cause a denial of service.

  • No authentication or user interaction required.
  • Triggered by visiting a malicious webpage or opening a crafted email.
  • Allows arbitrary code execution or denial of service.

Live Threat

Current exploitation, exposure, and threat context

When supported by the advisory, a use-after-free vulnerability in the Graphics: WebGPU component could affect sensitive information and service behavior. This could occur when processing web content, potentially impacting the integrity and availability of the affected application.

  • User data or system integrity may be affected.
  • Malicious web content could trigger the vulnerability.
  • Application instability or data corruption could occur.

Operational Fix

Recommended remediation, mitigation, and detection steps

Application owners, particularly those responsible for managing user-facing software like web browsers and email clients, should take the lead. The initial focus should be on identifying all instances of the affected software, assessing their reachability and criticality to business operations, and then confirming the specific accountable owner for each deployment. Planning for remediation should follow, prioritized by risk.

  • Accountable owners must be identified.
  • Verify software reachability and criticality.
  • Plan remediation based on identified risk.

Supplementary metadata

PCI scan relevance

Yes

CVE-2026-12293 — Halo PCI Relevance: Yes. Under typical PCI ASV external scan criteria, this issue may be flagged for scan prioritization.

This use-after-free vulnerability in the Graphics: WebGPU component could allow remote code execution, making it a critical issue for PCI compliance. Such vulnerabilities often lead to automatic failure in PCI ASV scans due to their severe impact on security.

Scan-prioritization guidance only—not a PCI DSS certification or ASV attestation.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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Frequently asked questions

What is the WebGPU component in Firefox and Thunderbird?

WebGPU is a graphics API built into Firefox and Thunderbird that allows web content to access the computer's graphics hardware. It is designed to accelerate complex rendering tasks, such as 3D graphics or data processing, directly within the browser or email interface. Because it acts as a bridge between web code and system hardware, it requires careful handling of memory to ensure that instructions are processed safely.

What does a use-after-free vulnerability mean for CVE-2026-12293?

This is a memory management error, specifically classified as CWE-416. It occurs when a program continues to use a memory location after it has been cleared or released. Because the application still references that memory, an attacker might be able to corrupt the program's state or run unauthorized instructions. In the context of this CVE, the Graphics component fails to manage these memory references correctly during processing.

How is this vulnerability triggered?

The flaw is triggered when the application processes specially crafted content that interacts with the WebGPU component. This typically happens if a user navigates to a malicious webpage or opens a crafted email that invokes the faulty graphics routine. Simply having the software installed is not enough to trigger the bug; the application must actively parse the malicious content for the memory error to manifest.

Who should be concerned about CVE-2026-12293?

Users and organizations relying on Firefox or Thunderbird should prioritize this issue. While Halo Surface Signal notes that these are client-side applications rather than public-facing network infrastructure, they are frequently exposed to external content via the internet. Anyone using these tools to browse the web or read emails faces potential risk if they encounter malicious material.

What should I do to address this vulnerability?

The primary response is to update your software to version 152 or higher. Since this flaw affects the core graphics handling of the application, identifying where Firefox and Thunderbird are deployed across your systems is the first step. Once you have an inventory, ensure that these applications are updated to the patched versions to remove the vulnerable code path.

References

Sources and related resources

Primary sources: NVD, CVE.org.

NVDPublished Modified