---
id: CVE-2026-8971
title: 'Same-origin policy bypass in the Networking: JAR component'
summary: >-
  Same-origin policy bypass in the Networking: JAR component. This vulnerability
  was fixed in Firefox 151 and Thunderbird 151.
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'
cwe:
  - CWE-346
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: '2026-07-23'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-8971'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=2032604'
    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: 0.00206
epssPercentile: 0.1101
ingestedAt: '2026-07-23T20:19:19.225Z'
---

## Overview

Same-origin policy bypass in the Networking: JAR 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`