---
title: "CVE-2019-18634\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-2019-18634?format=md
keywords: index, follow
---

# CVE-2019-18634

Publication date 31 January 2020

Last updated 25 August 2025

---

Ubuntu priority

**Low**

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

## Cvss 3 Severity Score

**7.8 · High**

[Score breakdown](https://ubuntu.com/security/CVE-2019-18634?format=md#impact-score)

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## Description

In Sudo before 1.8.26, if pwfeedback is enabled in /etc/sudoers, users can
trigger a stack-based buffer overflow in the privileged sudo process.
(pwfeedback is a default setting in Linux Mint and elementary OS; however,
it is NOT the default for upstream and many other packages, and would exist
only if enabled by an administrator.) The attacker needs to deliver a long
string to the stdin of getln() in tgetpass.c.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2019-18634?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| sudo | 19.10 eoan | Fixed 1.8.27-1ubuntu4.1 |
| 18.04 LTS bionic | Fixed 1.8.21p2-3ubuntu1.2 |
| 16.04 LTS xenial | Fixed 1.8.16-0ubuntu1.9 |
| 14.04 LTS trusty | Fixed 1.8.9p5-1ubuntu1.5+esm3  Ubuntu Pro |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)
* [Patch details](https://ubuntu.com/security/CVE-2019-18634?format=md#patch-details)

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## Notes

---

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

pwfeedback is not enabled in Ubuntu
affects 1.7.1 to 1.8.25p1 as it can't be exploited in 1.8.26 to
1.8.30

### Patch details

For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)

| Package | Patch details |
| --- | --- |
| sudo | * Upstream:   [fa8ffeb](https://github.com/sudo-project/sudo/commit/fa8ffeb17523494f0e8bb49a25e53635f4509078) |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

7.8 · High

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 7.8 · High |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-18634)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2019-18634)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2019-18634)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2019-18634)

### Related Ubuntu Security Notices (USN)

+ [USN-4263-2](https://usn.ubuntu.com/USN-4263-2)
+ Sudo vulnerability
+ 5 February 2020

+ [USN-4263-1](https://usn.ubuntu.com/USN-4263-1)
+ Sudo vulnerability
+ 3 February 2020

### Other references

* <https://www.openwall.com/lists/oss-security/2020/01/30/6>
* <https://www.openwall.com/lists/oss-security/2020/01/31/1>
* <https://www.cve.org/CVERecord?id=CVE-2019-18634>