---
title: "CVE-2015-8623\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-2015-8623?format=md
keywords: index, follow
---

# CVE-2015-8623

Publication date 23 March 2017

Last updated 25 August 2025

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**8.8 · High**

[Score breakdown](https://ubuntu.com/security/CVE-2015-8623?format=md#impact-score)

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## Description

The User::matchEditToken function in includes/User.php in MediaWiki before
1.23.12 and 1.24.x before 1.24.5 does not perform token comparison in
constant time before returning, which allows remote attackers to guess the
edit token and bypass CSRF protection via a timing attack, a different
vulnerability than CVE-2015-8624.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| mediawiki | 19.04 disco | Not affected |
| 18.10 cosmic | Not affected |
| 18.04 LTS bionic | Not affected |
| 17.10 artful | Ignored end of life |
| 17.04 zesty | Ignored end of life |
| 16.10 yakkety | Ignored end of life |
| 16.04 LTS xenial | Not in release |
| 15.10 wily | Ignored end of life |
| 15.04 vivid | Ignored end of life |
| 14.04 LTS trusty | Not in release |
| 12.04 LTS precise | Ignored end of life |

---

* [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**

8.8 · High

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 8.8 · High |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-8623)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2015-8623)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2015-8623)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2015-8623)

### Other references

* <https://gerrit.wikimedia.org/r/#/c/156336/5/includes/User.php>
* <https://www.cve.org/CVERecord?id=CVE-2015-8623>