---
title: "CVE-2019-14842\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-2019-14842?format=md
keywords: index, follow
---

# CVE-2019-14842

Publication date 26 November 2019

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-2019-14842?format=md#impact-score)

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## Description

Structured reply is a feature of the newstyle NBD protocol allowing the
server to send a reply in chunks. A bounds check which was supposed to test
for chunk offsets smaller than the beginning of the request did not work
because of signed/unsigned confusion. If one of these chunks contains a
negative offset then data under control of the server is written to memory
before the read buffer supplied by the client. If the read buffer is
located on the stack then this allows the stack return address from
nbd\_pread() to be trivially modified, allowing arbitrary code execution
under the control of the server. If the buffer is located on the heap then
other memory objects before the buffer can be overwritten, which again
would usually lead to arbitrary code execution.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| libnbd | 19.10 eoan | Not in release |
| 19.04 disco | Not in release |
| 18.04 LTS bionic | Not in release |
| 16.04 LTS xenial | Not in release |
| 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**

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:3.1/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-2019-14842)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2019-14842)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2019-14842)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2019-14842)

### Other references

* <https://www.redhat.com/archives/libguestfs/2019-October/msg00060.html>
* <https://github.com/libguestfs/libnbd/commit/f75f602a6361c0c5f42debfeea6980f698ce7f09 (1.1.4)>
* <https://github.com/libguestfs/libnbd/commit/2c1987fc23d6d0f537edc6d4701e95a2387f7917 (stable-1.0)>
* <https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-14842>
* <https://www.cve.org/CVERecord?id=CVE-2019-14842>