CVE-2024-47886: Chamilo LMS RCE Vulnerability

CVE-2024-47886 Overview

CVE-2024-47886 is an insecure deserialization vulnerability affecting Chamilo, a popular open-source learning management system (LMS). The vulnerability exists in versions 1.11.12 through 1.11.26 and allows authenticated administrators to achieve remote code execution (RCE) on the server through a post-authentication phar unserialize attack vector. By abusing multiple supported features from the vchamilo virtualization plugin, an attacker with administrative access can execute arbitrary code on the underlying server.

Critical Impact

Authenticated administrators can leverage the vchamilo plugin to trigger phar deserialization, leading to complete server compromise and arbitrary code execution.

Affected Products

• Chamilo LMS versions 1.11.12 through 1.11.26
• Systems utilizing the vchamilo virtualization plugin
• Self-hosted Chamilo LMS deployments

Discovery Timeline

• 2026-03-02 - CVE CVE-2024-47886 published to NVD
• 2026-03-03 - Last updated in NVD database

Technical Details for CVE-2024-47886

Vulnerability Analysis

This vulnerability represents a classic insecure deserialization flaw (CWE-502) that exploits PHP's phar stream wrapper functionality. Chamilo LMS contains features within the vchamilo virtualization plugin that process user-controllable input through PHP's unserialization mechanism. When a malicious phar archive is processed by the application, the embedded serialized PHP objects are automatically deserialized, allowing an attacker to leverage existing PHP classes (gadget chains) to achieve arbitrary code execution.

The attack requires administrative access to the Chamilo LMS platform, which positions this as a post-authentication exploit. However, the impact is severe as it enables complete server takeover, potentially affecting all users and data within the learning management system.

Root Cause

The root cause of CVE-2024-47886 lies in improper handling of file operations within the vchamilo plugin. PHP's phar stream wrapper automatically deserializes metadata when phar archives are accessed through various file functions (such as file_exists(), is_dir(), file_get_contents(), etc.). The application fails to validate or sanitize input that gets passed to these file operations, allowing attackers to supply a phar:// wrapper pointing to a malicious archive. When the phar metadata is deserialized, any available gadget chains in the application's codebase can be triggered to execute arbitrary code.

Attack Vector

The attack is network-accessible and requires an authenticated administrator session. The attacker must craft a malicious phar archive containing serialized PHP objects that form a gadget chain compatible with the classes available in Chamilo LMS or its dependencies. The attack flow involves:

1. The attacker authenticates as an administrator to the Chamilo LMS platform
2. A malicious phar archive is uploaded or made accessible to the server
3. The vchamilo plugin features are abused to trigger file operations on the malicious phar path
4. PHP's phar stream wrapper deserializes the embedded metadata
5. The gadget chain executes, leading to arbitrary code execution on the server

The vulnerability requires no user interaction beyond the initial authentication step and operates over the network, making it a significant threat to organizations running vulnerable Chamilo installations.

Detection Methods for CVE-2024-47886

Indicators of Compromise

• Unusual file operations involving phar:// stream wrappers in web server logs
• Unexpected file uploads with .phar extensions or phar-like binary signatures
• Administrative actions targeting vchamilo plugin functionality outside normal usage patterns
• New or modified files in web-accessible directories following administrative plugin usage

Detection Strategies

• Monitor web application logs for requests containing phar:// URI patterns in parameters
• Implement file integrity monitoring on the Chamilo installation directory
• Review administrative access logs for unusual vchamilo plugin interactions
• Deploy web application firewall (WAF) rules to detect phar deserialization attack patterns

Monitoring Recommendations

• Enable detailed logging for administrative actions within Chamilo LMS
• Monitor PHP error logs for deserialization-related warnings or exceptions
• Implement network monitoring for unexpected outbound connections from the web server
• Track process execution events originating from the web server user account

How to Mitigate CVE-2024-47886

Immediate Actions Required

• Upgrade Chamilo LMS to version 1.11.28 or later immediately
• Audit administrative user accounts and remove unnecessary privileges
• Review recent administrative activity for signs of exploitation
• Consider temporarily disabling the vchamilo plugin until patching is complete

Patch Information

Chamilo has addressed this vulnerability in version 1.11.28. Organizations should upgrade to the latest available release to ensure protection against this and potentially related vulnerabilities. The patch information and release notes are available through the GitHub Release v1.11.28. Additional details about the security fix can be found in the GitHub Security Advisory GHSA-c4fc-vjm9-9mvc.

Workarounds

• Restrict administrative access to trusted personnel only and implement multi-factor authentication
• If not required, disable or remove the vchamilo virtualization plugin
• Implement network segmentation to limit the blast radius of potential server compromise
• Consider placing Chamilo behind a reverse proxy with phar-aware filtering capabilities

# Configuration example - Disable phar wrapper in PHP (if not required)
# Add to php.ini or pool configuration
# Note: This may break legitimate phar functionality
disable_functions = phar://