---
title: "CVE-2018-20187\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-2018-20187?format=md
keywords: index, follow
---

# CVE-2018-20187

Publication date 8 March 2019

Last updated 26 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-2018-20187?format=md#impact-score)

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## Description

A side-channel issue was discovered in Botan before 2.9.0. An attacker
capable of precisely measuring the time taken for ECC key generation may be
able to derive information about the high bits of the secret key, as the
function to derive the public point from the secret scalar uses an
unblinded Montgomery ladder whose loop iteration count depends on the
bitlength of the secret. This issue affects only key generation, not ECDSA
signatures or ECDH key agreement.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| botan | 26.04 LTS resolute | Not in release |
| 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 | Not in release |
| 14.04 LTS trusty | Not in release |
| botan1.10 | 26.04 LTS resolute | Not in release |
| 25.10 questing | Not in release |
| 25.04 plucky | Not in release |
| 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release |
| 23.10 mantic | Not in release |
| 23.04 lunar | Not in release |
| 22.10 kinetic | Not in release |
| 22.04 LTS jammy | Not in release |
| 21.10 impish | Not in release |
| 21.04 hirsute | Not in release |
| 20.10 groovy | Not in release |
| 20.04 LTS focal | Not in release |
| 19.10 eoan | Not in release |
| 19.04 disco | Not in release |
| 18.10 cosmic | Ignored end of life |
| 18.04 LTS bionic | Not affected |
| 16.04 LTS xenial | Not affected |
| 14.04 LTS trusty | Needs evaluation |

---

* [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**

5.9 · Medium

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | Attack complexity | High |
  | Privileges required | None |
  | User interaction | None |
  | Scope | Unchanged |
  | Confidentiality impact | High |
  | Integrity impact | None |
  | 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:H/I:N/A:N

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-20187)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2018-20187)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2018-20187)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2018-20187)

### Other references

* <https://github.com/randombit/botan/pull/1792>
* <https://github.com/randombit/botan/commit/70aa7303acfff9eefc24598c289a84db3579ebd1>
* <https://www.cve.org/CVERecord?id=CVE-2018-20187>