---
id: CVE-2026-109757
title: Sandbox escape due to race condition in the Networking component
summary: >-
  Sandbox escape due to race condition in the Networking component. This
  vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158,
  and Thunderbird 153.5.
severity: high
cvss: 8.3
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H'
cwe:
  - CWE-362
vendor: Mozilla
product: Firefox
affected:
  - Firefox
  - Thunderbird
published: '2026-10-13'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T20:17:08.243'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-109757'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=2069910'
    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
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-109/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-110/'
    label: security@mozilla.org
tags:
  - nvd
  - cve.org
epss: 0.00258
epssPercentile: 0.17354
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-15T19:56:25.886376Z'
ingestedAt: '2026-10-13T13:27:04.009Z'
---

## Overview

Sandbox escape due to race condition in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

## Remediation

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