--- title: "CVE-2021-23976\n | Ubuntu" description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/CVE-2021-23976?format=md keywords: index, follow --- # CVE-2021-23976 Publication date 26 February 2021 Last updated 25 August 2025 --- Ubuntu priority **Medium** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) ## Cvss 3 Severity Score **8.1 · High** [Score breakdown](https://ubuntu.com/security/CVE-2021-23976?format=md#impact-score) Toggle side navigation ## Description When accepting a malicious intent from other installed apps, Firefox for Android accepted manifests from arbitrary file paths and allowed declaring webapp manifests for other origins. This could be used to gain fullscreen access for UI spoofing and could also lead to cross-origin attacks on targeted websites. Note: This issue is a different issue from CVE-2020-26954 and only affected Firefox for Android. Other operating systems are unaffected. This vulnerability affects Firefox < 86. [Read the notes from the security team](https://ubuntu.com/security/CVE-2021-23976?format=md#notes) ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | firefox | 24.04 LTS noble | Not affected | | 23.10 mantic | Not affected | | 23.04 lunar | Not affected | | 22.10 kinetic | Not affected | | 22.04 LTS jammy | Not affected | | 21.10 impish | Not affected | | 21.04 hirsute | Not affected | | 20.10 groovy | Not affected | | 20.04 LTS focal | Not in release | | 18.04 LTS bionic | Not affected | | 16.04 LTS xenial | Not affected | | 14.04 LTS trusty | Not in release | | mozjs38 | 24.04 LTS noble | Not in release | | 23.10 mantic | Not in release | | 23.04 lunar | Not in release | | 22.10 kinetic | Not in release | | 22.04 LTS jammy | Not in release | | 21.10 impish | Not in release | | 21.04 hirsute | Not in release | | 20.10 groovy | Not in release | | 20.04 LTS focal | Not in release | | 18.04 LTS bionic | Ignored | | 16.04 LTS xenial | Not in release | | 14.04 LTS trusty | Not in release | | mozjs52 | 24.04 LTS noble | Not in release | | 23.10 mantic | Not in release | | 23.04 lunar | Not in release | | 22.10 kinetic | Not in release | | 22.04 LTS jammy | Not in release | | 21.10 impish | Not in release | | 21.04 hirsute | Not in release | | 20.10 groovy | Ignored end of life | | 20.04 LTS focal | Ignored | | 18.04 LTS bionic | Ignored | | 16.04 LTS xenial | Not in release | | 14.04 LTS trusty | Not in release | | mozjs60 | 24.04 LTS noble | Not in release | | 23.10 mantic | Not in release | | 23.04 lunar | Not in release | | 22.10 kinetic | Not in release | | 22.04 LTS jammy | Not in release | | 21.10 impish | Not in release | | 21.04 hirsute | Not in release | | 20.10 groovy | Not in release | | 20.04 LTS focal | Not in release | | 18.04 LTS bionic | Not in release | | 16.04 LTS xenial | Not in release | | 14.04 LTS trusty | Not in release | | mozjs68 | 24.04 LTS noble | Not in release | | 23.10 mantic | Not in release | | 23.04 lunar | Not in release | | 22.10 kinetic | Not in release | | 22.04 LTS jammy | Not in release | | 21.10 impish | Not in release | | 21.04 hirsute | Not in release | | 20.10 groovy | Ignored end of life | | 20.04 LTS focal | Ignored | | 18.04 LTS bionic | Not in release | | 16.04 LTS xenial | Not in release | | 14.04 LTS trusty | Not in release | | mozjs78 | 24.04 LTS noble | Not in release | | 23.10 mantic | Not in release | | 23.04 lunar | Ignored end of life, was needs-triage | | 22.10 kinetic | Ignored end of life, was needs-triage | | 22.04 LTS jammy | Ignored | | 21.10 impish | Ignored end of life | | 21.04 hirsute | Ignored end of life | | 20.10 groovy | Ignored end of life | | 20.04 LTS focal | Not in release | | 18.04 LTS bionic | Not in release | | 16.04 LTS xenial | Not in release | | 14.04 LTS trusty | Not in release | --- * [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) * [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses) ## Notes --- ### [tyhicks](https://launchpad.net/~tyhicks) mozjs contains a copy of the SpiderMonkey JavaScript engine ## Severity score breakdown CVSS version: CVSS v3.0 **Base score** 8.1 · High * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Network | | Attack complexity | Low | | Privileges required | None | | User interaction | Required | | Scope | Unchanged | | Confidentiality impact | High | | Integrity impact | High | | Availability impact | None | * Scores | Parameter | Value | | --- | --- | | Base score | 8.1 · High | | Exploitability score | - | | Impact score | - | **Vector:** CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23976) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2021-23976) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2021-23976) * [Debian](https://security-tracker.debian.org/tracker/CVE-2021-23976) ### Other references * * * *