---
title: "CVE-2018-15599\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-2018-15599?format=md
keywords: index, follow
---

# CVE-2018-15599

Publication date 21 August 2018

Last updated 26 August 2025

---

Ubuntu priority

**Low**

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

## Cvss 3 Severity Score

**5.3 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2018-15599?format=md#impact-score)

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## Description

The recv\_msg\_userauth\_request function in svr-auth.c in Dropbear through
2018.76 is prone to a user enumeration vulnerability because username
validity affects how fields in SSH\_MSG\_USERAUTH messages are handled, a
similar issue to CVE-2018-15473 in an unrelated codebase.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| dropbear | 26.04 LTS resolute | Not affected |
| 25.10 questing | Not affected |
| 25.04 plucky | Not affected |
| 24.10 oracular | Not affected |
| 24.04 LTS noble | Not affected |
| 23.10 mantic | Not affected |
| 23.04 lunar | Not affected |
| 22.10 kinetic | Not affected |
| 22.04 LTS jammy | Not affected |
| 21.10 impish | Not affected |
| 21.04 hirsute | Not affected |
| 20.10 groovy | Not affected |
| 20.04 LTS focal | Not affected |
| 19.10 eoan | Not affected |
| 19.04 disco | Not affected |
| 18.10 cosmic | Ignored end of life |
| 18.04 LTS bionic | Vulnerable |
| 16.04 LTS xenial | Vulnerable |
| 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)

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

5.3 · Medium

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 5.3 · Medium |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-15599)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2018-15599)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2018-15599)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2018-15599)

### Other references

* <http://lists.ucc.gu.uwa.edu.au/pipermail/dropbear/2018q3/002108.html>
* <http://lists.ucc.gu.uwa.edu.au/pipermail/dropbear/2018q3/002109.html>
* <https://old.reddit.com/r/blackhat/comments/97ywnm/openssh_username_enumeration/e4e05n2/>
* <https://www.cve.org/CVERecord?id=CVE-2018-15599>