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CVE-2026-34161

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

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 2.0.0-RC.3
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • chamilo chamilo-lms

    fixed in 2.0.0-RC.3

References 4

GitHub · chamilo/chamilo-lms