---
id: CVE-2026-8961
title: Spoofing issue in the Form Autofill component
summary: >-
  Spoofing issue in the Form Autofill component. This vulnerability was fixed in
  Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N'
cwe:
  - CWE-290
vendor: mozilla
product: firefox
affected:
  - firefox < 140.11.0
  - firefox < 151.0.0
  - thunderbird < 140.11
  - thunderbird < 151.0.0
patched:
  - firefox 151.0.0
  - thunderbird 151.0.0
published: '2026-05-19'
updated: '2026-07-23'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-8961'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1962625'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-46/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-48/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-50/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-51/'
    label: security@mozilla.org
tags:
  - nvd
epss: 0.00322
epssPercentile: 0.25528
ingestedAt: '2026-07-23T20:19:18.993Z'
---

## Overview

Spoofing issue in the Form Autofill component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

## Affected

- `firefox < 140.11.0`
- `firefox < 151.0.0`
- `thunderbird < 140.11`
- `thunderbird < 151.0.0`

## Remediation

Upgrade past the affected range:

- `firefox 151.0.0`
- `thunderbird 151.0.0`