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Joomla\!Application · Joomla

CVE-2020-11891

MEDIUM · 5.3 CVSS v3.1 Published 2020-04-21
Fix available
A fix is available. Upgrade to 3.9.17 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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
An issue was discovered in Joomla! before 3.9.17. Incorrect ACL checks in the access level section of com_users allow the unauthorized editing of usergroups.

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

This is an Access Control List (ACL) bypass vulnerability in Joomla's com_users component. The access level section contains incorrect permission checks that allow authenticated users to edit usergroups they should not have access to modify, potentially leading to privilege escalation through unauthorized modification of access permissions.

MitigationUpgrade to Joomla! version 3.9.17 or later, which contains the corrected ACL validation logic in the com_users access level section.

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
Joomla\!Application
Affected:>= 3.8.8, < 3.9.17

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
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

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

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. Identify installed Joomla version
    Locate the version.php file in the Joomla installation (typically at /libraries/cms/version.php or check the administrator manifest cache in the database). Run: SELECT manifest_cache FROM #__extensions WHERE type = 'plugin' AND element = 'system' LIMIT 1;
    Affected if The reported version is >= 3.8.8 and < 3.9.17
  2. Confirm com_users component is present
    Verify the com_users component is installed and enabled. Check the #__extensions table for the users component: SELECT enabled FROM #__extensions WHERE type = 'component' AND element = 'com_users';
    Affected if The com_users component is enabled (value = 1)
  3. Verify user account access to component
    Check if the Joomla site allows user registration or has existing authenticated user accounts. Examine the users table: SELECT COUNT(*) FROM #__users WHERE block = 0;
    Affected if Any authenticated users exist in the system who could potentially access the vulnerable access level section

The environment is affected if the installed Joomla version is between 3.8.8 and 3.9.16 inclusive, the com_users component is enabled, and authenticated users exist who could exploit the incorrect ACL permission checks in the access level section.

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.

From vendor data
Upgrade available Upgrade to 3.9.17 or later
Fixed in 3.9.17
Interim mitigation

Upgrade to Joomla! version 3.9.17 or later, which contains the corrected ACL validation logic in the com_users access level section.

Fix this in Joomla\! Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
8.0 hours of engineering $1,370
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,192.

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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-2020-11891 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