---
id: CVE-2025-5020
title: >-
  Opening maliciously-crafted URLs in Firefox from other apps such as Safari
  could have allowed attackers to spoof website addresses if the URLs utilized
  non-HTTP schemes used internally by the Firefox iOS client
summary: >-
  Opening maliciously-crafted URLs in Firefox from other apps such as Safari
  could have allowed attackers to spoof website addresses if the URLs utilized
  non-HTTP schemes used internally by the Firefox iOS client. This vulnerability
  was fi…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N'
cwe:
  - CWE-939
vendor: mozilla
product: firefox
affected:
  - firefox < 139.0
patched:
  - firefox 139.0
published: '2025-05-21'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T18:10:00.190'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-5020'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1951558'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-39/'
    label: security@mozilla.org
tags:
  - nvd
epss: 0.00226
epssPercentile: 0.12002
ingestedAt: '2026-09-30T18:17:24.438Z'
---

## Overview

Opening maliciously-crafted URLs in Firefox from other apps such as Safari could have allowed attackers to spoof website addresses if the URLs utilized non-HTTP schemes used internally by the Firefox iOS client. This vulnerability was fixed in Firefox for iOS 139.

## Affected

- `firefox < 139.0`

## Remediation

Upgrade past the affected range:

- `firefox 139.0`