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MoodleCMS

CVE-2019-3809

CRITICAL · 10.0 CVSS v3.0 Published 2019-03-25
Fix available
A fix is available. Upgrade to after 3.1.15 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

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
A flaw was found in Moodle versions 3.1 to 3.1.15 and earlier unsupported versions. The mybackpack functionality allowed setting the URL of badges, when it should be restricted to the Mozilla Open Badges backpack URL. This resulted in the possibility of blind SSRF via requests made by the page.

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 · high confidence

The mybackpack functionality in Moodle versions 3.1 to 3.1.15 failed to restrict badge URL parameters to only the Mozilla Open Badges backpack URL. This allowed attackers to specify arbitrary URLs, causing the server to make blind SSRF requests to attacker-controlled endpoints without returning the response.

MitigationUpgrade to a patched Moodle version. Until then, restrict or disable the mybackpack functionality for untrusted users and implement URL allowlisting to only permit requests to the legitimate Mozilla Open Badges backpack domain.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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:>= 3.1.0, <= 3.1.15

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
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Moodle version
    Access the site administration panel and navigate to Site administration > Server > Environment, or check the version.php file in the Moodle root directory. Compare the version number to the affected range 3.1.0 through 3.1.15.
    Affected if The installed version falls within 3.1.0 to 3.1.15 inclusive.
  2. Determine if mybackpack functionality is accessible
    Verify whether the mybackpack feature is enabled in the system. This typically involves checking if users can access the 'My backpack' section within their profile or badge settings.
    Affected if The mybackpack feature is enabled and accessible to users.
  3. Check badge backpack URL configuration
    Navigate to Site administration > Badges > Backpack settings and examine the configured Open Badges backpack URL.
    Affected if Users with badge management privileges can modify or specify arbitrary URLs beyond the legitimate Mozilla Open Badges backpack domain.
  4. Identify user roles with access to badge functionality
    Review which user roles have permission to manage badges or configure backpack settings. Check the capabilities assigned to roles such as teacher, manager, or any custom roles.
    Affected if Untrusted or low-privilege users have the capability to configure or access the mybackpack functionality.

You are affected if your Moodle installation runs version 3.1.0 through 3.1.15 AND the mybackpack feature is enabled and accessible to users who can specify arbitrary URLs for the badge backpack.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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
Upgrade available Upgrade to a release after 3.1.15
Vendor patch git.moodle.org →
Interim mitigation

Upgrade to a patched Moodle version. Until then, restrict or disable the mybackpack functionality for untrusted users and implement URL allowlisting to only permit requests to the legitimate Mozilla Open Badges backpack domain.

Recommended fix High confidence

Moodle 3.1.16 or later

  1. Identify the current Moodle version by checking the version.php file in the Moodle root directory or the Site Administration > Server > Environment page
  2. Download Moodle 3.1.16 or a later stable version from https://download.moodle.org/releases/stable/
  3. Create a full backup of the Moodle database, moodledata directory, and code files before proceeding
  4. Place the site in maintenance mode via Site Administration > Server > Maintenance Mode
  5. Replace the Moodle code files with the new version, preserving the config.php file and any local customizations
  6. Complete the upgrade by running the upgrade process via web browser (visit admin/index.php) or command line (php admin/cli/upgrade.php)
  7. Verify the fix by confirming the mybackpack functionality now properly validates and restricts badge backpack URLs to the Mozilla Open Badges backpack URL
  8. Exit maintenance mode
Caveat Minor version upgrades typically have minimal breaking changes; review the release notes for any configuration or feature changes

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

Fix this in Moodle Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,408.

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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-2019-3809 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data