CVE-2024-40749: Joomla! Auth Bypass Vulnerability

CVE-2024-40749 Overview

CVE-2024-40749 is an improper access control vulnerability affecting Joomla! that permits unauthenticated network attackers to read content from protected core views. The flaw stems from access control list (ACL) violations across multiple core views in the Joomla! content management system. Successful exploitation discloses information that should be restricted to authorized users, breaching the confidentiality boundary enforced by Joomla! ACLs. The vulnerability is classified under [CWE-284] Improper Access Control and impacts confidentiality without affecting integrity or availability. Administrators running affected Joomla! installations should apply the vendor security update promptly to prevent unauthorized data exposure.

Critical Impact

Unauthenticated remote attackers can read information from Joomla! views protected by access control lists, leading to disclosure of sensitive site content.

Affected Products

• Joomla! CMS (standard support branch)
• Joomla! CMS (Extended Long Term Support / ELTS branch)
• Joomla! core views enforcing ACL read restrictions

Discovery Timeline

• 2025-01-07 - CVE-2024-40749 published to NVD
• 2025-06-04 - Last updated in NVD database

Technical Details for CVE-2024-40749

Vulnerability Analysis

The vulnerability exists in multiple Joomla! core views that fail to properly enforce access control list checks before returning data. Joomla! uses ACLs to determine which user groups can view specific content, components, and administrative resources. Affected views skip or incorrectly evaluate these checks during request handling. As a result, an unauthenticated attacker issuing crafted requests over the network can retrieve information that should require authentication or specific group membership. The issue impacts confidentiality only and does not enable modification of data or denial of service. The Exploit Prediction Scoring System places this issue in a low-likelihood band for near-term exploitation, but the unauthenticated network attack surface makes opportunistic scanning plausible.

Root Cause

The root cause is missing or incomplete ACL enforcement in several Joomla! core view classes. The application logic returns view data without first validating that the requesting session has the required core.admin, core.manage, or component-specific permissions. This maps to [CWE-284] Improper Access Control.

Attack Vector

Exploitation occurs over the network with low complexity and requires no authentication or user interaction. An attacker sends standard HTTP requests targeting the vulnerable Joomla! view endpoints. The server returns content that should be gated by ACL rules. No exploit code has been published in public databases at the time of writing, and the CVE is not listed in the CISA Known Exploited Vulnerabilities catalog.

No verified proof-of-concept code is available. Refer to the Joomla Security Advisory for vendor-provided technical detail on the affected views.

Detection Methods for CVE-2024-40749

Indicators of Compromise

• Unauthenticated HTTP GET requests to Joomla! core view endpoints originating from unknown source IP addresses.
• Web server access logs showing successful 200 OK responses to view requests without a preceding authenticated session.
• Unusual outbound transfers of view payloads to single client IPs across short timeframes.

Detection Strategies

• Audit Joomla! installation version against fixed releases listed in the vendor advisory.
• Correlate web server logs with session and authentication logs to identify view access without valid login tokens.
• Deploy web application firewall rules that flag access to administrative or restricted view paths from unauthenticated sessions.

Monitoring Recommendations

• Forward Joomla! application logs and web server access logs to a centralized SIEM for retention and correlation.
• Alert on spikes in index.php view parameter access patterns that deviate from baseline user behavior.
• Track repeated requests to component views from non-authenticated clients as a probable enumeration indicator.

How to Mitigate CVE-2024-40749

Immediate Actions Required

• Upgrade Joomla! to the fixed version identified in the vendor security advisory immediately.
• Inventory all Joomla! instances, including ELTS deployments, and prioritize internet-facing sites.
• Review web server logs for evidence of unauthenticated access to protected views prior to patching.

Patch Information

The Joomla! Project released fixes addressing the read ACL violation across multiple core views. Patch details and fixed version numbers are documented in the Joomla Security Advisory. Apply the update through the Joomla! administrator update component or by deploying the patched package manually.

Workarounds

• If immediate patching is not possible, restrict access to the Joomla! site using IP allowlisting at the web server or WAF layer.
• Block public access to administrative and component view URLs that are not required by anonymous users.
• Enforce authentication at the reverse proxy for sensitive content pending the official update.

# Example: restrict Joomla administrator views at the reverse proxy
location ~* ^/(administrator|index\.php\?option=com_) {
    allow 203.0.113.0/24;
    deny all;
}