Attack Chain

1. An attacker authenticates to the Chamilo LMS platform with valid user credentials.
2. The attacker crafts a malicious URL targeting an internal service or resource.
3. The attacker initiates a POST request to the read_url_with_open_graph endpoint.
4. The POST request includes the crafted URL within the social_wall_new_msg_main parameter.
5. The Chamilo LMS server, without proper validation, processes the POST request.
6. The server then makes an HTTP request to the attacker-supplied URL.
7. If the URL targets an internal service, the attacker may gain unauthorized access or information.
8. Successful exploitation allows the attacker to scan internal ports and potentially access cloud instance metadata, leading to further reconnaissance or lateral movement.

Impact

Successful exploitation of this SSRF vulnerability could allow an attacker to gain unauthorized access to internal services and data within the organization’s network. An attacker could use this vulnerability to enumerate internal systems, gather sensitive information, and potentially escalate privileges within the network. This could also lead to lateral movement, data exfiltration, or other malicious activities. The severity of the impact depends on the sensitivity of the internal services exposed and the attacker’s objectives.

Recommendation

• Upgrade Chamilo LMS to version 1.11.38 or 2.0.0-RC.3 or later to patch CVE-2026-31941.
• Implement network segmentation to limit the impact of potential SSRF attacks.
• Monitor web server logs for POST requests to /main/social/social_wall/social_wall.ajax.php with unusual URLs in the social_wall_new_msg_main parameter to detect potential exploitation attempts.
• Deploy the Sigma rule to detect requests with unusual URLs to social_wall.ajax.php.