CVE-2025-59544: Chamilo LMS Auth Bypass Vulnerability

CVE-2025-59544 Overview

CVE-2025-59544 is a Missing Authorization vulnerability affecting Chamilo LMS, an open-source learning management system. Prior to version 1.11.34, the functionality that allows users to update categories fails to implement proper authorization checks for the category_id parameter. This oversight enables any authenticated user to modify the category assignments of other users by simply manipulating the category_id parameter in requests.

Critical Impact

Unauthorized users can modify category assignments for any user in the system, potentially disrupting organizational structures and user management within the learning management platform.

Affected Products

• Chamilo LMS versions prior to 1.11.34
• chamilo chamilo_lms (cpe:2.3:a:chamilo:chamilo_lms::::::::)

Discovery Timeline

• 2026-03-06 - CVE-2025-59544 published to NVD
• 2026-03-09 - Last updated in NVD database

Technical Details for CVE-2025-59544

Vulnerability Analysis

This vulnerability is classified under CWE-862 (Missing Authorization), which occurs when software does not perform an authorization check when an actor attempts to access a resource or perform an action. In this case, Chamilo LMS exposes a category update endpoint that accepts a category_id parameter without validating whether the requesting user has the authority to modify that particular category assignment.

The vulnerability allows attackers to perform horizontal privilege escalation by manipulating category assignments across the user base. While the data integrity impact is limited to category modifications, this could have significant implications for organizations that rely on category-based access controls or organizational hierarchies within their learning management deployments.

Root Cause

The root cause of this vulnerability is the absence of server-side authorization validation in the category update functionality. The application accepts the category_id parameter from user input and processes the update request without verifying that the authenticated user owns or has permission to modify the specified category. This represents a classic Insecure Direct Object Reference (IDOR) pattern combined with missing authorization checks.

Attack Vector

The attack is network-accessible and requires no user interaction. An attacker with any level of authenticated access to the Chamilo LMS platform can exploit this vulnerability by intercepting or crafting HTTP requests to the category update endpoint. By substituting their own category_id with that of another user's category, the attacker can successfully modify category assignments they should not have access to.

The exploitation process involves:

1. Authenticating to the Chamilo LMS platform with any valid user account
2. Identifying the category update endpoint and capturing a legitimate request
3. Modifying the category_id parameter to reference another user's category
4. Submitting the modified request to alter the target user's category assignment

Detection Methods for CVE-2025-59544

Indicators of Compromise

• Unexpected changes to user category assignments without corresponding administrative actions
• Anomalous API requests to category update endpoints with varying category_id values from single user sessions
• Audit log entries showing category modifications by users without administrative privileges
• Pattern of sequential or enumerated category_id values in request logs from individual users

Detection Strategies

• Monitor web application logs for category update requests where the authenticated user ID does not match the expected owner of the category_id
• Implement alerting on bulk category modification requests from non-administrative accounts
• Deploy web application firewall (WAF) rules to detect parameter tampering patterns in category-related endpoints
• Review database audit logs for unexpected UPDATE operations on category tables

Monitoring Recommendations

• Enable detailed request logging for all category management endpoints including full parameter capture
• Configure alerts for category modifications performed outside of normal administrative workflows
• Implement user behavior analytics to detect unusual patterns of category access or modification
• Establish baseline metrics for category update frequency and alert on statistical anomalies

How to Mitigate CVE-2025-59544

Immediate Actions Required

• Upgrade Chamilo LMS to version 1.11.34 or later immediately
• Audit recent category modifications to identify any unauthorized changes
• Review user category assignments for integrity and correct any anomalies discovered
• Consider temporarily restricting access to category management features until the patch is applied

Patch Information

Chamilo has addressed this vulnerability in version 1.11.34. The fix implements proper authorization checks to ensure users can only modify categories they own or have explicit permission to manage. Organizations should upgrade to this version or later to remediate the vulnerability.

For detailed information about the fix, refer to the GitHub Security Advisory GHSA-x3h9-h7qf-wwrf and the GitHub Release v1.11.34.

Workarounds

• Implement a reverse proxy or WAF rule to validate that category_id parameters in update requests belong to the authenticated user
• Restrict network access to the Chamilo LMS instance to trusted IP ranges until patching is complete
• Temporarily disable category self-service features if operationally feasible
• Implement additional application-level logging to capture and alert on suspicious category modification attempts

# Example: Restrict access to category endpoints via Apache configuration
# Add to virtual host configuration until patch is applied
<Location "/main/inc/ajax/categories.ajax.php">
    Require ip 10.0.0.0/8 192.168.0.0/16
    # Restrict to internal administrative networks only
</Location>