---
id: CVE-2020-26977
title: >-
  By attempting to connect a website using an unresponsive port, an attacker
  could have controlled the content of a tab while the URL bar displayed the
  original domain
summary: >-
  By attempting to connect a website using an unresponsive port, an attacker
  could have controlled the content of a tab while the URL bar displayed the
  original domain. *Note: This issue only affects Firefox for Android. Other
  operating sy…
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'
vendor: mozilla
product: firefox_mobile
affected:
  - firefox_mobile < 84.0
patched:
  - firefox_mobile 84.0
published: '2021-01-07'
updated: '2026-08-19'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2020-26977'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1676311'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2020-54/'
    label: security@mozilla.org
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1676311'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.mozilla.org/security/advisories/mfsa2020-54/'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00851
epssPercentile: 0.56713
ingestedAt: '2026-08-19T15:41:15.154Z'
---

## Overview

By attempting to connect a website using an unresponsive port, an attacker could have controlled the content of a tab while the URL bar displayed the original domain. *Note: This issue only affects Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 84.

## Affected

- `firefox_mobile < 84.0`

## Remediation

Upgrade past the affected range:

- `firefox_mobile 84.0`