# CVE-2026-90913: Joomla Core improper ACL checks in webservice endpoints

Source: https://junglewise.ai/threats/cve-2026-90913-joomla-core-20260903-core-improper-acl-checks-for-access-level  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-29. Updated: 2026-09-29  
License: CC BY 4.0 with a link back

CVE-2026-90913 · Severity: info · Published 2026-09-29

Joomla is a widely-used content management system that powers millions of websites. An access control flaw in the webservice endpoints allows unauthorized users to modify access level settings, potentially granting themselves elevated privileges or disrupting site permissions. An attacker could exploit this remotely without authentication to gain administrative control over affected websites.

Technologies: [Joomla! Joomla\!](https://junglewise.ai/threats/technologies/joomla). Vendors: [Joomla!](https://junglewise.ai/threats/vendors/joomla).

## Quick answers

**Is CVE-2026-90913 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-90913 being exploited in the wild.

**How severe is CVE-2026-90913?** Informational severity, published 29 September 2026.

**Which products and versions are affected?** Joomla! Joomla\! 4.0.0-5.4.8, 6.0.0-6.1.3.

**Is there a fix for CVE-2026-90913?** A patch was published on 2026-09-25: Fixed in versions 5.4.9 and 6.1.4 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-90913 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-90913?** Check whether you run Joomla! Joomla\! at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An improper access control check in Joomla's webservice endpoints for access level management fails to validate user permissions before allowing mutation actions. The vulnerability exists in the core API handlers and can be exploited over the network without prior authentication. A successful exploit allows an attacker to modify access level configurations, potentially escalating privileges or disabling access controls.

## Affected products

- Joomla Joomla 4.0.0-5.4.8, 6.0.0-6.1.3

## Timeline

- 2026-09-29: disclosed
- 2026-09-25: patched: Fixed in versions 5.4.9 and 6.1.4

## References

- [https://developer.joomla.org/security-centre/1083-20260903-core-improper-acl-checks-for-user-level-webservice-endpoints.html](https://developer.joomla.org/security-centre/1083-20260903-core-improper-acl-checks-for-user-level-webservice-endpoints.html)
- [https://www.joomla.org/](https://www.joomla.org/)

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