CVE-2026-16384: Firefox WebGPU Information Disclosure

CVE-2026-16384 Overview

CVE-2026-16384 is an information disclosure vulnerability in the Graphics: WebGPU component of Mozilla Firefox and Thunderbird. The flaw stems from the use of uninitialized memory ([CWE-908]), which allows an attacker to read residual data from memory regions that were never properly initialized before use. Mozilla addressed the issue in Firefox 153 and Thunderbird 153. The vulnerability is network-exploitable and requires no privileges or user interaction, according to the CVSS vector.

Critical Impact
A remote attacker can trigger the vulnerable WebGPU code path through crafted web content to leak sensitive process memory contents from the browser.

Affected Products

Mozilla Firefox versions prior to 153
Mozilla Thunderbird versions prior to 153
Applications embedding the vulnerable WebGPU implementation

Discovery Timeline

2026-07-21 - CVE-2026-16384 published to NVD
2026-07-22 - Last updated in NVD database

Technical Details for CVE-2026-16384

Vulnerability Analysis

The vulnerability resides in the WebGPU implementation within the Graphics subsystem of Gecko-based products. WebGPU exposes GPU compute and rendering capabilities to web content through JavaScript APIs. During specific WebGPU operations, memory buffers are allocated and returned to the caller without being fully initialized. This creates a window where uninitialized bytes containing prior heap or stack contents become accessible to JavaScript running in the renderer process. Attackers can read those bytes and reconstruct sensitive information such as pointers, tokens, or fragments of user data.

Root Cause

The root cause is classified under [CWE-908] Use of Uninitialized Resource. The affected WebGPU code path allocates a memory region intended to hold output data but returns it to script context before all bytes are written by the intended operation. Because the underlying allocator reuses memory across the process, the returned buffer may contain residue from prior allocations. Mozilla's fix ensures the buffers are zero-initialized or fully written before exposure to JavaScript, as documented in Mozilla Bug Report #2041911.

Attack Vector

Exploitation requires only that a victim visit an attacker-controlled or compromised web page in a vulnerable Firefox build. The page loads JavaScript that requests a WebGPU adapter, creates the affected resource type, and reads back the uninitialized bytes. No authentication or user interaction beyond page load is required. The attack does not modify data or impact availability, which aligns with the confidentiality-only impact profile of this issue. Details on the exploitation surface are described in Mozilla Security Advisory MFSA-2026-68 and Mozilla Security Advisory MFSA-2026-71.

Detection Methods for CVE-2026-16384

Indicators of Compromise

Outbound HTTP/HTTPS requests from Firefox processes carrying base64-encoded or binary payloads shortly after WebGPU API usage
Browser telemetry showing repeated calls to WebGPU buffer readback methods from untrusted origins
Firefox versions below 153 or Thunderbird versions below 153 running in the environment

Detection Strategies

Inventory installed Firefox and Thunderbird builds and flag any host running versions earlier than 153
Monitor endpoint process telemetry for firefox.exe or thunderbird.exe child processes spawning with WebGPU enabled while running vulnerable versions
Correlate web proxy logs to identify sites invoking WebGPU APIs against clients that have not been patched

Monitoring Recommendations

Enable browser version reporting through endpoint management tooling to track patch compliance
Alert on execution of Firefox binaries whose file version metadata indicates a pre-153 release
Review DNS and TLS SNI logs for connections to untrusted domains delivering WebGPU-heavy content to unpatched clients

How to Mitigate CVE-2026-16384

Immediate Actions Required

Update Firefox to version 153 or later on all managed endpoints
Update Thunderbird to version 153 or later where installed
Push the update through enterprise deployment tooling and validate installed versions across the fleet

Patch Information

Mozilla released fixed builds in Firefox 153 and Thunderbird 153. Full advisory details are available in Mozilla Security Advisory MFSA-2026-68 and Mozilla Security Advisory MFSA-2026-71. The underlying code change is tracked in Mozilla Bug Report #2041911.

Workarounds

Disable WebGPU by setting dom.webgpu.enabled to false in about:config until patching is complete
Restrict WebGPU-capable sites through enterprise browser policy where full patch rollout is delayed
Block or sandbox untrusted web content using network-level controls for hosts that cannot be updated immediately

bash

# Firefox enterprise policy example to disable WebGPU
# policies.json
{
  "policies": {
    "Preferences": {
      "dom.webgpu.enabled": {
        "Value": false,
        "Status": "locked"
      }
    }
  }
}