Medium 5.1Published Apr 14, 2026

CVE-2026-34161Chamilo LMS: Stored XSS via Malicious File Upload in Social Post Attachments Leads to Arbitrary JavaScript Execution

Updated under an hour ago (Oct 26, 2026, 8:00 PM ET)

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Every CVE for chamilo-lms

Exploited in the last 30 days

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.

CVSS: 5.1 MEDIUM (v4.0, CNA)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
Weakness (CWE): CWE-79
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Apr 16, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

chamilo chamilo-lms chamilo:lms (from the name)	before 2.0.0-RC.3	CNA record
chamilo chamilo_lms chamilo:chamilo_lms	through 1.11.38; 2.0.0; 2.0.0; 2.0.0; 2.0.0; 2.0.0; 2.0.0; 2.0.0; and 3 more ranges	NVD

References

References

https://github.com/chamilo/chamilo-lms/security/advisories/GHSA-273p-jw9w-3g22	x-refsource-confirm, vendor-advisory
https://github.com/chamilo/chamilo-lms/commit/7c4965e48769d1d06413836429e386816a465c7f	x-refsource-misc, patch
https://github.com/chamilo/chamilo-lms/commit/da671d66a146887be3a16eabc5dcf0a92c55f7da	x-refsource-misc, patch
https://github.com/chamilo/chamilo-lms/releases/tag/v2.0.0-RC.3	x-refsource-misc, product, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.