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MoodleCMS

CVE-2021-36568

MEDIUM · 5.4 CVSS v3.1 Published 2022-09-13
No fix yet
No fix has been published. The vendor has not shipped a fixed release or patch. You remain exposed.
See remediation →
58/100
Remediation priority · Elevated
Public exploit Remotely reachable

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In certain Moodle products after creating a course, it is possible to add in a arbitrary "Topic" a resource, in this case a "Database" with the type "Text" where its values "Field name" and "Field description" are vulnerable to Cross Site Scripting Stored(XSS). This affects Moodle 3.11 and Moodle 3.10.4 and Moodle 3.9.7.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-79

Untrusted input is placed into a web page without being neutralised, so an attacker's markup or script executes in another user's browser. That can hijack sessions, capture keystrokes, or silently perform actions as the victim. Fixing it properly means context-aware output encoding everywhere data meets HTML, backed by a content-security policy as a second line of defence.

General guidance for the cross-site scripting (xss) class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
MoodleCMS
Affected:= 3.9.7= 3.10.4= 3.11.0
FedoraOperating system
Affected:= 35= 36

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Recommended fix Moderate confidence

Moodle 3.9.8+ / 3.10.5+ / 3.11.1+ (or latest stable 3.x release)

  1. 1. Back up your Moodle database and file store before performing any upgrade.
  2. 2. Download the appropriate Moodle version from https://download.moodle.org/
  3. 3. For Moodle 3.9.x: Upgrade to at least version 3.9.8 or later.
  4. 4. For Moodle 3.10.x: Upgrade to at least version 3.10.5 or later.
  5. 5. For Moodle 3.11.x: Upgrade to at least version 3.11.1 or later.
  6. 6. After upgrading, navigate to Site administration > Plugins > Activity modules > Database and verify the Database activity module is updated.
  7. 7. Clear all Moodle caches via Site administration > Development > Purge caches.
  8. 8. Test that creating a Database activity module with Text field type does not allow XSS payloads in Field name or Field description.
Caveat Standard Moodle minor version upgrades are generally low-risk, but always test in staging first; some plugins may require updates for compatibility with newer Moodle versions

Generated from the published advisory — verify against the referenced sources before acting.

No vendor fix exists Moodle has not published a patch for this.

There is no version to upgrade to and no patch to apply. Every affected install stays exposed until the vendor ships a fix — or somebody else builds one.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-36568 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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