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.

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Tue, 14 Apr 2026 21:15:00 +0000

Type Values Removed Values Added
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.
Title Chamilo LMS: Stored XSS via Malicious File Upload in Social Post Attachments Leads to Arbitrary JavaScript Execution
Weaknesses CWE-79
References
Metrics cvssV4_0

{'score': 5.1, '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'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-04-14T21:12:48.128Z

Reserved: 2026-03-25T20:12:04.197Z

Link: CVE-2026-34161

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-04-14T21:16:26.400

Modified: 2026-04-14T21:16:26.400

Link: CVE-2026-34161

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses