--- title: "CVE-2021-23969\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-2021-23969?format=md keywords: index, follow --- # CVE-2021-23969 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 **4.3 · Medium** [Score breakdown](https://ubuntu.com/security/CVE-2021-23969?format=md#impact-score) Toggle side navigation ## Description As specified in the W3C Content Security Policy draft, when creating a violation report, "User agents need to ensure that the source file is the URL requested by the page, pre-redirects. If that’s not possible, user agents need to strip the URL down to an origin to avoid unintentional leakage." Under certain types of redirects, Firefox incorrectly set the source file to be the destination of the redirects. This was fixed to be the redirect destination's origin. This vulnerability affects Firefox < 86, Thunderbird < 78.8, and Firefox ESR < 78.8. [Read the notes from the security team](https://ubuntu.com/security/CVE-2021-23969?format=md#notes) ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | 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 end of standard support, was needs-triage | | 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 end of standard support, was needs-triage | | 16.04 LTS xenial | Not in release | | 14.04 LTS trusty | Not in release | | firefox | 24.04 LTS noble | Fixed 86.0+build3-0ubuntu1 | | 23.10 mantic | Fixed 86.0+build3-0ubuntu1 | | 23.04 lunar | Fixed 86.0+build3-0ubuntu1 | | 22.10 kinetic | Fixed 86.0+build3-0ubuntu1 | | 22.04 LTS jammy | Fixed 86.0+build3-0ubuntu1 | | 21.10 impish | Fixed 86.0+build3-0ubuntu1 | | 21.04 hirsute | Fixed 86.0+build3-0ubuntu1 | | 20.10 groovy | Fixed 86.0+build3-0ubuntu0.20.10.1 | | 20.04 LTS focal | Fixed 86.0+build3-0ubuntu0.20.04.1 | | 18.04 LTS bionic | Fixed 86.0+build3-0ubuntu0.18.04.1 | | 16.04 LTS xenial | Fixed 86.0+build3-0ubuntu0.16.04.1 | | 14.04 LTS trusty | Not in release | | firefox-esr | 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 | | 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 | | thunderbird | 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 | Fixed 1:78.8.1+build1-0ubuntu0.20.10.1 | | 20.04 LTS focal | Fixed 1:78.8.1+build1-0ubuntu0.20.04.1 | | 18.04 LTS bionic | Fixed 1:78.8.1+build1-0ubuntu0.18.04.1 | | 16.04 LTS xenial | Ignored end of standard support, was needed | | 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** 4.3 · Medium * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Network | | Attack complexity | Low | | Privileges required | None | | User interaction | Required | | Scope | Unchanged | | Confidentiality impact | Low | | Integrity impact | None | | Availability impact | None | * Scores | Parameter | Value | | --- | --- | | Base score | 4.3 · Medium | | Exploitability score | - | | Impact score | - | **Vector:** CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23969) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2021-23969) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2021-23969) * [Debian](https://security-tracker.debian.org/tracker/CVE-2021-23969) ### Related Ubuntu Security Notices (USN) + [USN-4756-1](https://usn.ubuntu.com/USN-4756-1) + Firefox vulnerabilities + 26 February 2021 + [USN-4936-1](https://usn.ubuntu.com/USN-4936-1) + Thunderbird vulnerabilities + 6 May 2021 ### Other references * * * * * * * *