---
title: "CVE-2016-5254\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-2016-5254?format=md
keywords: index, follow
---

# CVE-2016-5254

Publication date 3 August 2016

Last updated 25 August 2025

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**9.8 · Critical**

[Score breakdown](https://ubuntu.com/security/CVE-2016-5254?format=md#impact-score)

Toggle side navigation

## Description

Use-after-free vulnerability in the nsXULPopupManager::KeyDown function in
Mozilla Firefox before 48.0 and Firefox ESR 45.x before 45.3 allows
attackers to execute arbitrary code or cause a denial of service (heap
memory corruption and application crash) by leveraging keyboard access to
use the Alt key during selection of top-level menu items.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| firefox | 16.04 LTS xenial | Fixed 48.0+build2-0ubuntu0.16.04.1 |
| 14.04 LTS trusty | Fixed 48.0+build2-0ubuntu0.14.04.1 |
| 12.04 LTS precise | Fixed 48.0+build2-0ubuntu0.12.04.1 |
| thunderbird | 16.04 LTS xenial | Not affected |
| 14.04 LTS trusty | Not in release |
| 12.04 LTS precise | Not affected |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

9.8 · Critical

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 9.8 · Critical |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-5254)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2016-5254)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2016-5254)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2016-5254)

### Related Ubuntu Security Notices (USN)

+ [USN-3044-1](https://usn.ubuntu.com/USN-3044-1)
+ Firefox vulnerabilities
+ 5 August 2016

### Other references

* <https://www.mozilla.org/en-US/security/advisories/mfsa2016-70/>
* <https://bugzilla.mozilla.org/show_bug.cgi?id=1266963>
* <https://www.cve.org/CVERecord?id=CVE-2016-5254>