---
title: "CVE-2018-12437\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-2018-12437?format=md
keywords: index, follow
---

# CVE-2018-12437

Publication date 15 June 2018

Last updated 25 August 2025

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**4.9 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2018-12437?format=md#impact-score)

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## Description

LibTomCrypt through 1.18.1 allows a memory-cache side-channel attack on
ECDSA signatures, aka the Return Of the Hidden Number Problem or ROHNP. To
discover an ECDSA key, the attacker needs access to either the local
machine or a different virtual machine on the same physical host.

### From the Ubuntu Security Team

It was discovered that LibTomCrypt incorrectly handled ECDSA signatures.
A local attacker could possibly use this issue to obtain sensitive
information.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| libtomcrypt | 18.04 LTS bionic | Fixed 1.18.1-1ubuntu0.1 |
| 17.10 artful | Ignored end of life |
| 16.04 LTS xenial | Fixed 1.17-7ubuntu0.1 |
| 14.04 LTS trusty | Fixed 1.17-5ubuntu0.1 |

---

* [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**

4.9 · Medium

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 4.9 · Medium |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-12437)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2018-12437)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2018-12437)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2018-12437)

### Other references

* <https://github.com/libtom/libtomcrypt/issues/407>
* <https://www.nccgroup.trust/us/our-research/technical-advisory-return-of-the-hidden-number-problem/>
* <https://www.cve.org/CVERecord?id=CVE-2018-12437>