CVE-2025-50199: Chamilo LMS Blind SSRF Vulnerability

CVE-2025-50199 Overview

CVE-2025-50199 is a blind Server-Side Request Forgery (SSRF) vulnerability affecting Chamilo, a widely-used open-source learning management system (LMS). The vulnerability exists in the /index.php endpoint and can be exploited via the openid_url POST parameter. Prior to version 1.11.30, attackers could leverage this flaw to make the server perform unauthorized requests to internal or external resources, potentially exposing sensitive information or enabling further attacks against internal infrastructure.

Critical Impact

This blind SSRF vulnerability allows unauthenticated attackers to probe internal network resources and potentially access sensitive systems behind the firewall, escalating attack capabilities within educational institutions.

Affected Products

• Chamilo LMS versions prior to 1.11.30
• All deployments using the OpenID authentication functionality
• Self-hosted and cloud-based Chamilo installations with default configurations

Discovery Timeline

• 2026-03-02 - CVE CVE-2025-50199 published to NVD
• 2026-03-03 - Last updated in NVD database

Technical Details for CVE-2025-50199

Vulnerability Analysis

This vulnerability is classified under CWE-918 (Server-Side Request Forgery), a web application security flaw that occurs when an application can be induced to make HTTP requests to an arbitrary domain of the attacker's choosing. In the case of CVE-2025-50199, the blind SSRF variant means that while the attacker cannot directly see the response content, they can still infer information based on timing, error messages, or behavioral differences.

The vulnerability resides in the OpenID authentication handler within the Chamilo LMS codebase. The openid_url parameter accepts user-supplied URLs without adequate validation or sanitization, allowing attackers to craft malicious requests that the server will execute on their behalf. This is particularly dangerous in educational environments where Chamilo LMS is commonly deployed, as it could allow attackers to map internal networks, access cloud metadata services, or interact with internal APIs.

Root Cause

The root cause of this vulnerability is improper input validation of the openid_url POST parameter in /index.php. The application fails to properly validate, sanitize, or restrict the URLs that can be specified through this parameter. Without URL scheme validation, blocklists for internal IP ranges, or proper domain whitelisting, the server will blindly make requests to any URL supplied by an attacker.

Attack Vector

The attack vector for CVE-2025-50199 is network-based and requires no authentication or user interaction. An attacker can craft a specially crafted POST request to the vulnerable endpoint, supplying a malicious URL in the openid_url parameter. The server will then attempt to connect to the specified URL, enabling various attack scenarios:

• Internal Network Scanning: Probing internal IP ranges to discover active services
• Cloud Metadata Access: Targeting cloud provider metadata endpoints (e.g., 169.254.169.254) to retrieve sensitive credentials
• Service Enumeration: Identifying internal services and their versions
• Port Scanning: Using response timing to determine open ports on internal systems

The vulnerability mechanism involves the server processing the openid_url parameter within the OpenID authentication flow. When a malicious URL is supplied, the server initiates an HTTP request to the attacker-controlled destination. Although response content is not returned to the attacker (blind SSRF), timing analysis and error-based techniques can be used to extract information. For detailed technical implementation, refer to the GitHub Security Advisory.

Detection Methods for CVE-2025-50199

Indicators of Compromise

• Unusual outbound HTTP requests from the Chamilo LMS server to internal IP addresses or cloud metadata endpoints
• Anomalous POST requests to /index.php with suspicious openid_url parameter values containing internal IP ranges or localhost references
• Network traffic showing connection attempts to non-standard ports or internal services from the web server
• Log entries indicating failed or unusual OpenID authentication attempts with malformed URLs

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block SSRF patterns in the openid_url parameter
• Deploy network monitoring to identify outbound connections from the Chamilo server to internal IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16)
• Configure intrusion detection systems (IDS) to alert on requests containing cloud metadata endpoints (169.254.169.254)
• Enable detailed application logging for the OpenID authentication module to capture suspicious URL patterns

Monitoring Recommendations

• Monitor outbound HTTP/HTTPS traffic from Chamilo LMS servers for connections to unexpected destinations
• Set up alerts for any requests to cloud provider metadata services from application servers
• Review web server access logs for unusual patterns in POST requests to /index.php
• Implement network segmentation monitoring to detect lateral movement attempts originating from the Chamilo server

How to Mitigate CVE-2025-50199

Immediate Actions Required

• Upgrade Chamilo LMS to version 1.11.30 or later immediately to remediate this vulnerability
• If immediate patching is not possible, consider disabling or restricting access to OpenID authentication functionality
• Implement network-level controls to restrict outbound connections from the Chamilo server to only necessary destinations
• Review server logs for any evidence of exploitation attempts targeting the /index.php endpoint

Patch Information

Chamilo has released version 1.11.30 which addresses this blind SSRF vulnerability. Administrators should download the patched version from the official Chamilo GitHub releases page and follow standard upgrade procedures. The security advisory with additional details is available in the GitHub Security Advisory GHSA-jv2w-m5r6-p52h.

Workarounds

• Disable the OpenID authentication functionality if not required for your deployment
• Implement a web application firewall (WAF) rule to block or sanitize the openid_url parameter
• Configure network-level egress filtering to prevent the server from making arbitrary outbound requests
• Use a reverse proxy to inspect and filter requests to the vulnerable endpoint

# Example: Apache mod_rewrite rule to block suspicious openid_url values
# Add to .htaccess or Apache configuration
RewriteEngine On
RewriteCond %{REQUEST_METHOD} POST
RewriteCond %{REQUEST_URI} ^/index\.php$
RewriteCond %{THE_REQUEST} openid_url=.*(?:localhost|127\.|10\.|172\.1[6-9]\.|172\.2[0-9]\.|172\.3[0-1]\.|192\.168\.|169\.254\.)
RewriteRule .* - [F,L]