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Joomla\!Application · Joomla

CVE-2026-48958

HIGH · 8.8 CVSS v3.1 Published 2026-07-07
Fix available
A fix is available. Upgrade to 5.4.7 / 6.1.2 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click 6 weeks old

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 improper access check allows unauthorized users to create custom fields via webservices endpoints.

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 · moderate confidence

This is an authorization bypass vulnerability where webservice endpoints fail to properly validate user permissions before allowing custom field creation. The improper access check permits unauthenticated or unauthorized users to manipulate the application's data schema through API calls.

MitigationImplement proper authentication and role-based authorization checks on all webservice endpoints that handle custom field creation, ensuring only users with appropriate permissions can modify the data model.

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:>= 4.0.0, < 5.4.7>= 6.0.0, < 6.1.2

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
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/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. Identify installed Joomla version
    Check the Joomla administrator dashboard under System > Information, or inspect the libraries/cms.php file for the VERSION constant, or run: php -r "require_once('libraries/cms.php'); echo VERSION;"
    Affected if The version is >= 4.0.0 and < 5.4.7, or >= 6.0.0 and < 6.1.2
  2. Confirm webservice API is enabled
    Check Joomla configuration for API settings: navigate to System > Manage > API Plugins and verify if the Web Services - Joomla or similar API plugin is enabled
    Affected if The webservice API plugin is enabled and the vulnerable endpoint is exposed
  3. Verify custom field API endpoint accessibility
    Inspect the routing configuration in your Joomla installation for custom field creation endpoints, typically under api/config/routes or check if /api/index.php/v1/customfield or similar paths accept POST requests without authentication
    Affected if The custom field creation endpoint accepts requests without requiring valid user authentication or valid token-based authorization
  4. Check for unauthorized custom fields in the database
    Query the #__fields table in the Joomla database to identify custom fields with creation dates or user IDs that do not correspond to legitimate administrator accounts
    Affected if Custom fields exist that were created by users lacking proper admin permissions or by anonymous/unknown users

You are affected if your Joomla version falls within 4.0.0-5.4.6 or 6.0.0-6.1.1, the webservice API is enabled, and the custom field endpoint can be accessed without proper authentication or authorization validation.

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 5.4.7 / 6.1.2 or later
Fixed in 5.4.76.1.2
Interim mitigation

Implement proper authentication and role-based authorization checks on all webservice endpoints that handle custom field creation, ensuring only users with appropriate permissions can modify the data model.

Recommended fix High confidence

Joomla! 5.4.7 or later; Joomla! 6.1.2 or later

  1. 1. Backup your Joomla! database and all files completely before proceeding with any upgrade
  2. 2. Review the Joomla! official upgrade documentation at developer.joomla.org for your specific version path
  3. 3. Ensure your current PHP version meets the requirements for the target version (5.4.7 for Joomla 5.x or 6.1.2 for Joomla 6.x)
  4. 4. Disable all third-party extensions that may conflict with the upgrade
  5. 5. For Joomla! 5.x: Upgrade to version 5.4.7 or later
  6. 6. For Joomla! 6.x: Upgrade to version 6.1.2 or later
  7. 7. Clear all caches after upgrade
  8. 8. Verify that the webservices endpoints now properly enforce access controls for custom field creation
Caveat Review Joomla! release notes for any breaking changes between your current version and the target version before upgrading

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

Fix this in Joomla\! Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.

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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-2026-48958 in production — separate from our analysis above.

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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