---
id: CVE-2026-92050
title: Sandbox escape due to race condition in the XPConnect component
summary: >-
  Sandbox escape due to race condition in the XPConnect component. This
  vulnerability was fixed in Firefox 156 and Thunderbird 156.
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H'
cwe:
  - CWE-362
  - CWE-368
vendor: Mozilla
product: Firefox
affected:
  - Firefox
  - Thunderbird
published: '2026-09-15'
updated: '2026-09-21'
sourceUpdated: '2026-09-21T18:17:13.537'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-92050'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=2061387'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-90/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-94/'
    label: security@mozilla.org
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92050.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-92050'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2533798'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-92050'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-92050'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-90/#CVE-2026-92050'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-94/#CVE-2026-92050'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-21T17:39:54.136153Z'
epss: 0.00142
epssPercentile: 0.03863
scores:
  nvd: 9.1
  vendor: 6.1
  adp: 9.1
ingestedAt: '2026-09-15T12:36:50.183Z'
---

## Overview

Sandbox escape due to race condition in the XPConnect component. This vulnerability was fixed in Firefox 156 and Thunderbird 156.

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, … · updated 2026-09-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92050.json)