---
id: CVE-2026-8960
title: Spoofing issue in WebExtensions
summary: >-
  Spoofing issue in WebExtensions. This vulnerability was fixed in Firefox 151
  and Thunderbird 151.
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N'
cwe:
  - CWE-290
vendor: mozilla
product: firefox
affected:
  - firefox < 151.0.0
  - thunderbird < 151.0.0
patched:
  - firefox 151.0.0
  - thunderbird 151.0.0
published: '2026-05-19'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T20:10:00.190'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-8960'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1940116'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-46/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-50/'
    label: security@mozilla.org
tags:
  - nvd
epss: 0.00403
epssPercentile: 0.32844
ingestedAt: '2026-10-14T20:53:12.318Z'
---

## Overview

Spoofing issue in WebExtensions. This vulnerability was fixed in Firefox 151 and Thunderbird 151.

## Affected

- `firefox < 151.0.0`
- `thunderbird < 151.0.0`

## Remediation

Upgrade past the affected range:

- `firefox 151.0.0`
- `thunderbird 151.0.0`