---
title: "CVE-2018-16857\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-2018-16857?format=md
keywords: index, follow
---

# CVE-2018-16857

Publication date 27 November 2018

Last updated 25 August 2025

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**5.9 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2018-16857?format=md#impact-score)

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## Description

Samba from version 4.9.0 and before version 4.9.3 that have AD DC
configurations watching for bad passwords (to restrict brute forcing of
passwords) in a window of more than 3 minutes may not watch for bad
passwords at all. The primary risk from this issue is with regards to
domains that have been upgraded from Samba 4.8 and earlier. In these cases
the manual testing done to confirm an organisation's password policies
apply as expected may not have been re-done after the upgrade.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2018-16857?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| samba | 18.10 cosmic | Not affected |
| 18.04 LTS bionic | Not affected |
| 16.04 LTS xenial | Not affected |
| 14.04 LTS trusty | 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)

## Notes

---

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

4.9.x only

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

5.9 · Medium

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 5.9 · Medium |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-16857)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2018-16857)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2018-16857)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2018-16857)

### Other references

* <https://www.samba.org/samba/security/CVE-2018-16857.html>
* <https://www.cve.org/CVERecord?id=CVE-2018-16857>