CVE-2026-34161

Chamilo LMS is an open-source learning management system. In versions prior to 2.0.0-RC.3, a Stored Cross-Site Scripting (XSS) vulnerability exists in the social post attachment upload functionality, where an authenticated user can upload a malicious HTML file containing JavaScript via the /api/social_post_attachments endpoint. The uploaded file is served back from the application at the generated contentUrl without sanitization, content type restrictions, or a Content-Disposition: attachment header, causing the JavaScript to execute in the browser within the application's origin. Because the payload is stored server-side and runs in the trusted origin, an attacker can perform session hijacking, account takeover, privilege escalation (if an admin views the link), and arbitrary actions on behalf of the victim. This issue has been fixed in version 2.0.0-RC.3.

The following products are affected by CVE-2026-34161 vulnerability.

Here, you will find a curated list of external links that provide in-depth information to CVE-2026-34161.

URL	Resource
https://github.com/chamilo/chamilo-lms/commit/7c4965e48769d1d06413836429e386816a465c7f
https://github.com/chamilo/chamilo-lms/commit/da671d66a146887be3a16eabc5dcf0a92c55f7da
https://github.com/chamilo/chamilo-lms/releases/tag/v2.0.0-RC.3
https://github.com/chamilo/chamilo-lms/security/advisories/GHSA-273p-jw9w-3g22