---
title: "CVE-2026-4690\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-2026-4690?format=md
keywords: index, follow
---

# CVE-2026-4690

Publication date 24 March 2026

Last updated 16 April 2026

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**8.6 · High**

[Score breakdown](https://ubuntu.com/security/CVE-2026-4690?format=md#impact-score)

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## Description

Sandbox escape due to incorrect boundary conditions, integer overflow in
the XPCOM component. This vulnerability was fixed in Firefox 149, Firefox
ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2026-4690?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| firefox | 26.04 LTS resolute | Not affected |
| 25.10 questing | Not affected |
| 24.04 LTS noble | Not affected |
| 22.04 LTS jammy | Not affected |
| mozjs102 | 26.04 LTS resolute | Not in release |
| 25.10 questing | Not in release |
| 24.04 LTS noble | Ignored |
| 22.04 LTS jammy | Ignored |
| mozjs115 | 26.04 LTS resolute | Not in release |
| 25.10 questing | Not in release |
| 24.04 LTS noble | Ignored |
| 22.04 LTS jammy | Not in release |
| mozjs38 | 26.04 LTS resolute | Not in release |
| 25.10 questing | Not in release |
| 24.04 LTS noble | Not in release |
| 22.04 LTS jammy | Not in release |
| 18.04 LTS bionic | Needs evaluation |
| mozjs52 | 26.04 LTS resolute | Not in release |
| 25.10 questing | Not in release |
| 24.04 LTS noble | Not in release |
| 22.04 LTS jammy | Not in release |
| 20.04 LTS focal | Ignored |
| 18.04 LTS bionic | Ignored |
| mozjs68 | 26.04 LTS resolute | Not in release |
| 25.10 questing | 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 |
| 24.04 LTS noble | Not in release |
| 22.04 LTS jammy | Ignored |
| mozjs91 | 26.04 LTS resolute | Not in release |
| 25.10 questing | Not in release |
| 24.04 LTS noble | Not in release |
| 22.04 LTS jammy | Ignored |
| thunderbird | 26.04 LTS resolute | Not affected |
| 25.10 questing | Not affected |
| 24.04 LTS noble | Not affected |
| 22.04 LTS jammy | Vulnerable |

---

* [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**

8.6 · High

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | Attack complexity | Low |
  | Privileges required | None |
  | User interaction | None |
  | Scope | Changed |
  | Confidentiality impact | None |
  | Integrity impact | None |
  | Availability impact | High |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 8.6 · High |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-4690)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-4690)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-4690)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2026-4690)

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2026-4690>
* <https://www.mozilla.org/en-US/security/advisories/mfsa2026-20/#CVE-2026-4690>
* <https://www.mozilla.org/en-US/security/advisories/mfsa2026-22/#CVE-2026-4690>
* <https://www.mozilla.org/en-US/security/advisories/mfsa2026-24/#CVE-2026-4690>
* <https://bugzilla.mozilla.org/show_bug.cgi?id=2016375>
* <https://www.mozilla.org/security/advisories/mfsa2026-20/>
* <https://www.mozilla.org/security/advisories/mfsa2026-21/>
* <https://www.mozilla.org/security/advisories/mfsa2026-22/>
* <https://www.mozilla.org/security/advisories/mfsa2026-23/>
* <https://www.mozilla.org/security/advisories/mfsa2026-24/>