---
title: "CVE-2021-20186\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-2021-20186?format=md
keywords: index, follow
---

# CVE-2021-20186

Publication date 28 January 2021

Last updated 26 August 2025

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**5.4 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2021-20186?format=md#impact-score)

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## Description

It was found in Moodle before version 3.10.1, 3.9.4, 3.8.7 and 3.5.16 that
if the TeX notation filter was enabled, additional sanitizing of TeX
content was required to prevent the risk of stored XSS.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| moodle | 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 |
| 18.04 LTS bionic | Vulnerable |
| 16.04 LTS xenial | Vulnerable |
| 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)
* [Patch details](https://ubuntu.com/security/CVE-2021-20186?format=md#patch-details)

### Patch details

For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)

| Package | Patch details |
| --- | --- |
| moodle | * Upstream:   <https://git.moodle.org/gw?p=moodle.git;a=commit;h=11e13d1629a960b431c7f0fbc64e504bd32ae01a> |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

5.4 · Medium

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 5.4 · Medium |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-20186)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2021-20186)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2021-20186)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2021-20186)

### Other references

* <https://moodle.org/mod/forum/discuss.php?d=417170>
* <https://www.cve.org/CVERecord?id=CVE-2021-20186>