---
id: CVE-2025-5263
title: >-
  Error handling for script execution was incorrectly isolated from web content,
  which could have allowed cross-origin leak attacks
summary: >-
  Error handling for script execution was incorrectly isolated from web content,
  which could have allowed cross-origin leak attacks. This vulnerability was
  fixed in Firefox 139, Firefox ESR 115.24, Firefox ESR 128.11, Thunderbird 139,
  and …
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N'
cwe:
  - CWE-346
vendor: mozilla
product: firefox
affected:
  - firefox < 115.24.0
  - firefox < 139.0
  - 'firefox >= 116.0, < 128.11.0'
patched:
  - firefox 128.11.0
published: '2025-05-27'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T18:10:00.190'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-5263'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1960745'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-42/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-43/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-44/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-45/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-46/'
    label: security@mozilla.org
  - url: 'https://lists.debian.org/debian-lts-announce/2025/05/msg00043.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2025/05/msg00046.html'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00247
epssPercentile: 0.1445
ingestedAt: '2026-09-30T18:17:24.438Z'
---

## Overview

Error handling for script execution was incorrectly isolated from web content, which could have allowed cross-origin leak attacks. This vulnerability was fixed in Firefox 139, Firefox ESR 115.24, Firefox ESR 128.11, Thunderbird 139, and Thunderbird 128.11.

## Affected

- `firefox < 115.24.0`
- `firefox < 139.0`
- `firefox >= 116.0, < 128.11.0`

## Remediation

Upgrade past the affected range:

- `firefox 128.11.0`