---
id: CVE-2026-8948
title: 'Same-origin policy bypass in the DOM: Networking component'
summary: >-
  Same-origin policy bypass in the DOM: Networking component. This vulnerability
  was fixed in Firefox 151 and Thunderbird 151.
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-942
  - CWE-79
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-2026-8948'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=2038803'
    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
  - url: 'https://access.redhat.com/security/cve/CVE-2026-8948'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2479850'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-8948.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
tags:
  - nvd
epss: 0.00452
epssPercentile: 0.37692
ingestedAt: '2026-10-14T20:53:12.314Z'
---

## Overview

Same-origin policy bypass in the DOM: Networking component. 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`