---
id: CVE-2026-109705
title: >-
  Sandbox escape, site isolation issue due to incorrect boundary conditions,
  use-after-free in the Networking component
summary: >-
  Sandbox escape, site isolation issue due to incorrect boundary conditions,
  use-after-free in the Networking component. This vulnerability was fixed in
  Firefox 158 and Firefox ESR 153.5.
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-416
published: '2026-10-13'
updated: '2026-10-13'
sourceUpdated: '2026-10-13T16:18:13.247'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-109705'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=2040905'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-106/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-108/'
    label: security@mozilla.org
tags:
  - nvd
ingestedAt: '2026-10-13T13:27:03.990Z'
---

## Overview

Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component. This vulnerability was fixed in Firefox 158 and Firefox ESR 153.5.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.