CVE-2026-33715 Chamilo LMS has Unauthenticated SSRF and Open Email Relay via install.ajax.php test_mailer action
Unauthenticated attackers can exploit an SSRF vulnerability in Chamilo LMS to access internal networks and use the server as an open email relay.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-33715?
CVE-2026-33715 is a high-severity server-side request forgery vulnerability in Chamilo Chamilo Lms, published on 14 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Chamilo LMS is an open-source learning management system. In version 2.0-RC.2, the file public/main/inc/ajax/install.ajax.php is accessible without authentication on fully installed instances because, unlike other AJAX endpoints, it does not include the global.inc.php file that performs authentication and installation-completed checks. Its test_mailer action accepts an arbitrary Symfony Mailer DSN string from POST data and uses it to connect to an attacker-specified SMTP server, enabling Server-Side Request Forgery (SSRF) into internal networks via the SMTP protocol. An unauthenticated attacker can also abuse this to weaponize the Chamilo server as an open email relay for phishing and spam campaigns, with emails appearing to originate from the server's IP address. Additionally, error responses from failed SMTP connections may disclose information about internal network topology and running services. This issue has been fixed in version 2.0.0-RC.3.
Which versions are affected by CVE-2026-33715?
It affects 1 product.
Products include Chamilo Chamilo Lms.
How do I fix CVE-2026-33715?
No fix has been published for CVE-2026-33715 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-33715 being exploited?
There is no known exploitation of CVE-2026-33715 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in Chamilo Chamilo Lms
Sources
Also known as GHSA-mxc9-9335-45mc.