Vulnerability · Published Apr 14, 2026 · Assigned by GitHub_M
CVE-2026-34161Chamilo LMS: Stored XSS via Malicious File Upload in Social Post Attachments Leads to Arbitrary JavaScript Execution
Medium 5.1
In plain English
A medium-severity cross-site scripting in chamilo-lms from chamilo. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities).
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| chamilo | chamilo-lms | < 2.0.0-RC.3 |
Weakness: CWE-79 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
References
- https://github.com/chamilo/chamilo-lms/security/advisories/GHSA-273p-jw9w-3g22 x_refsource_CONFIRM
- https://github.com/chamilo/chamilo-lms/commit/7c4965e48769d1d06413836429e386816a465c7f x_refsource_MISC
- https://github.com/chamilo/chamilo-lms/commit/da671d66a146887be3a16eabc5dcf0a92c55f7da x_refsource_MISC
- https://github.com/chamilo/chamilo-lms/releases/tag/v2.0.0-RC.3 x_refsource_MISC