---
title: "CVE-2018-6829\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-2018-6829?format=md
keywords: index, follow
---

# CVE-2018-6829

Publication date 7 February 2018

Last updated 25 August 2025

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**7.5 · High**

[Score breakdown](https://ubuntu.com/security/CVE-2018-6829?format=md#impact-score)

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## Description

cipher/elgamal.c in Libgcrypt through 1.8.2, when used to encrypt messages
directly, improperly encodes plaintexts, which allows attackers to obtain
sensitive information by reading ciphertext data (i.e., it does not have
semantic security in face of a ciphertext-only attack). The Decisional
Diffie-Hellman (DDH) assumption does not hold for Libgcrypt's ElGamal
implementation.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2018-6829?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| gnupg | 18.04 LTS bionic | Not in release |
| 17.10 artful | Not in release |
| 16.04 LTS xenial | Not affected |
| 14.04 LTS trusty | Not affected |
| libgcrypt11 | 18.04 LTS bionic | Not in release |
| 17.10 artful | Not in release |
| 16.04 LTS xenial | Not in release |
| 14.04 LTS trusty | Not affected |
| libgcrypt20 | 18.04 LTS bionic | Not affected |
| 17.10 artful | Not affected |
| 16.04 LTS xenial | Not affected |
| 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)

## Notes

---

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

this is a flaw in applications that misuse libgcrypt
as of 2018-05-31, no actionable action in libgcrypt, marking as
not-affected

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

7.5 · High

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 7.5 · High |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-6829)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2018-6829)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2018-6829)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2018-6829)

### Other references

* <https://github.com/weikengchen/attack-on-libgcrypt-elgamal>
* <https://github.com/weikengchen/attack-on-libgcrypt-elgamal/wiki>
* <https://lists.gnupg.org/pipermail/gcrypt-devel/2018-February/004394.html>
* <https://lists.gnupg.org/pipermail/gcrypt-devel/2018-February/004401.html>
* <https://www.cve.org/CVERecord?id=CVE-2018-6829>