---
title: "CVE-2017-7761\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-2017-7761?format=md
keywords: index, follow
---

# CVE-2017-7761

Publication date 11 June 2018

Last updated 25 August 2025

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**5.5 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2017-7761?format=md#impact-score)

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## Description

The Mozilla Maintenance Service "helper.exe" application creates a
temporary directory writable by non-privileged users. When this is combined
with creation of a junction (a form of symbolic link), protected files in
the target directory of the junction can be deleted by the Mozilla
Maintenance Service, which has privileged access. Note: This attack
requires local system access and only affects Windows. Other operating
systems are not affected. This vulnerability affects Firefox ESR < 52.2 and
Firefox < 54.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2017-7761?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| firefox | 17.04 zesty | Not affected |
| 16.10 yakkety | Not affected |
| 16.04 LTS xenial | Not affected |
| 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

---

### [chrisccoulson](https://launchpad.net/~chrisccoulson)

Windows only

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

5.5 · Medium

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 5.5 · Medium |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-7761)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2017-7761)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2017-7761)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2017-7761)

### Other references

* <https://www.mozilla.org/en-US/security/advisories/mfsa2017-15/>
* <https://www.cve.org/CVERecord?id=CVE-2017-7761>