---
id: CVE-2026-92071
title: >-
  Sandbox escape due to incorrect boundary conditions in the Widget: Win32
  component
summary: >-
  Sandbox escape due to incorrect boundary conditions in the Widget: Win32
  component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3,
  Thunderbird 156, and Thunderbird 153.3.
severity: critical
cvss: 9.6
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H'
cwe:
  - CWE-119
  - CWE-501
vendor: mozilla
product: firefox
affected:
  - firefox < 153.3.0
  - 'firefox >= 154.0.0, < 156.0.0'
  - thunderbird < 153.3.0
  - 'thunderbird >= 154.0, < 156.0'
patched:
  - firefox 156.0.0
  - thunderbird 156.0
published: '2026-09-15'
updated: '2026-10-05'
sourceUpdated: '2026-10-05T19:40:32.353'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-92071'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=2061231'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-90/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-93/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-94/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-96/'
    label: security@mozilla.org
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92071.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-92071'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2533733'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-92071'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-92071'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-90/#CVE-2026-92071'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-94/#CVE-2026-92071'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00239
epssPercentile: 0.14933
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-22T15:25:58.982715Z'
scores:
  nvd: 9.6
  vendor: 3.4
  adp: 9.6
ingestedAt: '2026-09-15T12:36:50.176Z'
---

## Overview

Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.

## Affected

- `firefox < 153.3.0`
- `firefox >= 154.0.0, < 156.0.0`
- `thunderbird < 153.3.0`
- `thunderbird >= 154.0, < 156.0`

## Remediation

Upgrade past the affected range:

- `firefox 156.0.0`
- `thunderbird 156.0`

## Vendor advisories

- **Red Hat VEX** · Low · updated 2026-09-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92071.json)