---
id: CVE-2026-92021
title: 'Use-after-free in the JavaScript Engine: JIT component'
summary: >-
  Use-after-free in the JavaScript Engine: JIT component. This vulnerability was
  fixed in Firefox ESR 140.16 and Thunderbird 140.16.
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
  - CWE-825
vendor: Mozilla
product: Firefox
affected:
  - Firefox
  - Thunderbird
published: '2026-09-15'
updated: '2026-09-20'
sourceUpdated: '2026-09-20T01:16:34.863'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-92021'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=2067208'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-92/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-95/'
    label: security@mozilla.org
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92021.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-92021'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2533774'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-92021'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-92021'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-92/#CVE-2026-92021'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-95/#CVE-2026-92021'
  - url: 'https://access.redhat.com/errata/RHSA-2026:69461'
  - url: 'https://access.redhat.com/errata/RHSA-2026:69462'
  - url: 'https://access.redhat.com/errata/RHSA-2026:70642'
  - url: 'https://access.redhat.com/errata/RHSA-2026:71652'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-20T00:16:26.664464Z'
epss: 0.00301
epssPercentile: 0.20361
scores:
  nvd: 8.8
  vendor: 7.5
  adp: 8.8
ingestedAt: '2026-09-15T12:36:50.193Z'
patched:
  - enterprise_linux_appstream_v_10
  - enterprise_linux_appstream_v_9
---

## Overview

Use-after-free in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox ESR 140.16 and Thunderbird 140.16.

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8 · updated 2026-09-24 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92021.json)
- **RHSA-2026:69461** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-09-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:69461)
- **RHSA-2026:69462** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-09-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:69462)
- **RHSA-2026:70642** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-09-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:70642)
- **RHSA-2026:71652** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8) · released 2026-09-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:71652)