---
id: CVE-2025-1019
title: >-
  The z-order of the browser windows could be manipulated to hide the fullscreen
  notification
summary: >-
  The z-order of the browser windows could be manipulated to hide the fullscreen
  notification. This could potentially be leveraged to perform a spoofing
  attack. This vulnerability was fixed in Firefox 135 and Thunderbird 135.
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N'
cwe:
  - CWE-1021
  - CWE-1021
vendor: mozilla
product: firefox
affected:
  - firefox < 135.0
  - 'thunderbird >= 131.0, < 135.0'
patched:
  - firefox 135.0
  - thunderbird 135.0
published: '2025-02-04'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T19:10:01.007'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-1019'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1940162'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-07/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-11/'
    label: security@mozilla.org
tags:
  - nvd
epss: 0.00362
epssPercentile: 0.27632
ingestedAt: '2026-09-30T19:21:07.225Z'
---

## Overview

The z-order of the browser windows could be manipulated to hide the fullscreen notification. This could potentially be leveraged to perform a spoofing attack. This vulnerability was fixed in Firefox 135 and Thunderbird 135.

## Affected

- `firefox < 135.0`
- `thunderbird >= 131.0, < 135.0`

## Remediation

Upgrade past the affected range:

- `firefox 135.0`
- `thunderbird 135.0`