---
title: "CVE-2018-16471\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-2018-16471?format=md
keywords: index, follow
---

# CVE-2018-16471

Publication date 13 November 2018

Last updated 25 August 2025

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**6.1 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2018-16471?format=md#impact-score)

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## Description

There is a possible XSS vulnerability in Rack before 2.0.6 and 1.6.11.
Carefully crafted requests can impact the data returned by the `scheme`
method on `Rack::Request`. Applications that expect the scheme to be
limited to 'http' or 'https' and do not escape the return value could be
vulnerable to an XSS attack. Note that applications using the normal
escaping mechanisms provided by Rails may not impacted, but applications
that bypass the escaping mechanisms, or do not use them may be vulnerable.

### From the Ubuntu Security Team

It was discovered that Rack incorrectly handled carefully crafted requests. A
remote attacker could use this issue to execute a cross-site scripting (XSS)
attack.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| ruby-rack | 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 | Fixed 1.6.4-4ubuntu0.1 |
| 16.04 LTS xenial | Fixed 1.6.4-3ubuntu0.1 |
| 14.04 LTS trusty | Fixed 1.5.2-3+deb8u3  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)

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## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

6.1 · Medium

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 6.1 · Medium |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-16471)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2018-16471)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2018-16471)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2018-16471)

### Related Ubuntu Security Notices (USN)

+ [USN-4089-1](https://usn.ubuntu.com/USN-4089-1)
+ Rack vulnerability
+ 7 August 2019

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2018-16471>