--- title: "CVE-2025-4091\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-2025-4091?format=md keywords: index, follow --- # CVE-2025-4091 Publication date 29 April 2025 Last updated 26 June 2026 --- 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-2025-4091?format=md#impact-score) Toggle side navigation ## Description Memory safety bugs present in Firefox 137, Thunderbird 137, Firefox ESR 128.9, and Thunderbird 128.9. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 138, Firefox ESR 128.10, Thunderbird 138, and Thunderbird 128.10. [Read the notes from the security team](https://ubuntu.com/security/CVE-2025-4091?format=md#notes) ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | mozjs52 | 26.04 LTS resolute | Not in release | | 25.10 questing | Not in release | | 25.04 plucky | Not in release | | 24.10 oracular | Not in release | | 24.04 LTS noble | Not in release | | 22.04 LTS jammy | Not in release | | 20.04 LTS focal | Needs evaluation | | 18.04 LTS bionic | Ignored | | firefox | 26.04 LTS resolute | Not affected | | 25.10 questing | Not affected | | 25.04 plucky | Not affected | | 24.10 oracular | Not affected | | 24.04 LTS noble | Not affected | | 22.04 LTS jammy | Not affected | | 20.04 LTS focal | Not in release | | mozjs102 | 26.04 LTS resolute | Not in release | | 25.10 questing | Not in release | | 25.04 plucky | Not in release | | 24.10 oracular | Not in release | | 24.04 LTS noble | Ignored | | 22.04 LTS jammy | Ignored | | 20.04 LTS focal | Not in release | | mozjs115 | 26.04 LTS resolute | Not in release | | 25.10 questing | Not in release | | 25.04 plucky | Ignored | | 24.10 oracular | Ignored | | 24.04 LTS noble | Ignored | | 22.04 LTS jammy | Not in release | | 20.04 LTS focal | Not in release | | mozjs38 | 26.04 LTS resolute | Not in release | | 25.10 questing | Not in release | | 25.04 plucky | Not in release | | 24.10 oracular | Not in release | | 24.04 LTS noble | Not in release | | 22.04 LTS jammy | Not in release | | 20.04 LTS focal | Not in release | | 18.04 LTS bionic | Needs evaluation | | mozjs68 | 26.04 LTS resolute | Not in release | | 25.10 questing | Not in release | | 25.04 plucky | Not in release | | 24.10 oracular | Not in release | | 24.04 LTS noble | Not in release | | 22.04 LTS jammy | Not in release | | 20.04 LTS focal | Ignored | | mozjs78 | 26.04 LTS resolute | Not in release | | 25.10 questing | Not in release | | 25.04 plucky | Not in release | | 24.10 oracular | Not in release | | 24.04 LTS noble | Not in release | | 22.04 LTS jammy | Ignored | | 20.04 LTS focal | Not in release | | mozjs91 | 26.04 LTS resolute | Not in release | | 25.10 questing | Not in release | | 25.04 plucky | Not in release | | 24.10 oracular | Not in release | | 24.04 LTS noble | Not in release | | 22.04 LTS jammy | Ignored | | 20.04 LTS focal | Not in release | | thunderbird | 26.04 LTS resolute | Not affected | | 25.10 questing | Not affected | | 25.04 plucky | Not affected | | 24.10 oracular | Not affected | | 24.04 LTS noble | Not affected | | 22.04 LTS jammy | Fixed 1:128.12.0+build1-0ubuntu0.22.04.1 | | 20.04 LTS focal | 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 --- ### [mdeslaur](https://launchpad.net/~mdeslaur) mozjs\* contain a copy of the SpiderMonkey JavaScript engine. It is not feasible to backport security fixes to the mozjs\* packages, as such, marking them as ignored. starting with Ubuntu 22.04, the firefox package is just a script that installs the Firefox snap starting with Ubuntu 24.04, the thunderbird package is just a script that installs the Thunderbird snap ## Severity score breakdown CVSS version: CVSS v3.0 **Base score** 8.1 · High * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Network | | Attack complexity | High | | Privileges required | None | | User interaction | None | | Scope | Unchanged | | Confidentiality impact | High | | Integrity impact | High | | Availability impact | High | * Scores | Parameter | Value | | --- | --- | | Base score | 8.1 · High | | Exploitability score | - | | Impact score | - | **Vector:** CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2025-4091) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2025-4091) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2025-4091) * [Debian](https://security-tracker.debian.org/tracker/CVE-2025-4091) ### Related Ubuntu Security Notices (USN) + [USN-7663-1](https://usn.ubuntu.com/USN-7663-1) + Thunderbird vulnerabilities + 22 July 2025 ### Other references * * * * * * * * *