---
title: "CVE-2018-0733\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-2018-0733?format=md
keywords: index, follow
---

# CVE-2018-0733

Publication date 27 March 2018

Last updated 25 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-2018-0733?format=md#impact-score)

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## Description

Because of an implementation bug the PA-RISC CRYPTO\_memcmp function is
effectively reduced to only comparing the least significant bit of each
byte. This allows an attacker to forge messages that would be considered as
authenticated in an amount of tries lower than that guaranteed by the
security claims of the scheme. The module can only be compiled by the HP-UX
assembler, so that only HP-UX PA-RISC targets are affected. Fixed in
OpenSSL 1.1.0h (Affected 1.1.0-1.1.0g).

[Read the notes from the security team](https://ubuntu.com/security/CVE-2018-0733?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| openssl | 17.10 artful | Not affected |
| 16.04 LTS xenial | Not affected |
| 14.04 LTS trusty | Not affected |
| openssl098 | 17.10 artful | Not in release |
| 16.04 LTS xenial | Not in release |
| 14.04 LTS trusty | Not in release |
| openssl1.0 | 17.10 artful | 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)

## Notes

---

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

"The module can only be compiled by the HP-UX assembler, so
that only HP-UX PA-RISC targets are affected."

## 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 | None |
  | Integrity impact | High |
  | 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:N/I:H/A:N

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-0733)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2018-0733)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2018-0733)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2018-0733)

### Other references

* <https://www.openssl.org/news/secadv/20180327.txt>
* <https://www.cve.org/CVERecord?id=CVE-2018-0733>