CVE-2026-23899
Published: 01 April 2026
Summary
CVE-2026-23899 is a high-severity Improper Access Control (CWE-284) vulnerability in Joomla Joomla\!. Its CVSS base score is 8.6 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 31.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 AC-3 (Access Enforcement) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-23899 is an improper access check vulnerability (CWE-284) in the Joomla core webservice endpoints, published on 2026-04-01. It enables unauthorized access to these endpoints and carries a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H), indicating high severity due to its network accessibility, low complexity, and potential for significant impacts across confidentiality, integrity, and availability.
The vulnerability can be exploited by an attacker with low privileges, such as an authenticated user, who requires only network access and no user interaction. Exploitation grants unauthorized access to sensitive webservice endpoints, allowing high-impact outcomes including data exposure, modification, or disruption of services on the affected Joomla instance.
The primary advisory from the Joomla Security Centre (https://developer.joomla.org/security-centre/1032-20260306-core-improper-access-check-in-webservice-endpoints.html) details the issue and likely includes patch recommendations for affected Joomla versions. Security practitioners should review this reference for specific mitigation guidance, such as applying updates to core components.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-17863
Vulnerability details
An improper access check allows unauthorized access to webservice endpoints.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Direct match to exploitation of a vulnerable public-facing web service endpoint in Joomla for unauthorized access and high-impact actions.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly addresses the improper access check by requiring the system to enforce approved authorizations for logical access to webservice endpoints.
Mandates identification, reporting, and correction of flaws like this improper access check vulnerability through timely patching of affected Joomla core components.
Limits damage from low-privilege exploitation by enforcing least privilege, restricting unauthorized access scope on webservice endpoints.