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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: Apr 14, 2026Updated: Apr 23, 2026 Sources: CVE List NVDCWE-79
5.4MEDIUM
NVD MITRE
EPSS Score
0.2%
Top 87.8%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:LUI:RS:CC:LI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:RUser Interaction
Required
Scope
S:CScope
Changed
Impact
C:LConfidentiality
Low
I:LIntegrity
Low
A:NAvailability
None
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Weaknesses

CWE-79

Affected Products

chamilo-lmschamilo
On-premWeb App
Enterprise Software / collaboration-groupware
chamilo lmschamilo
On-premWeb App
Enterprise Software / itsm-monitoring
chamilooss-projectEnterprise Softwareaka chamilo-lms

Exploitability

Official Patch Available

Attack Graph

Products CVE Techniques Tactics

Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.

MITRE ATT&CK

2 techniques
Execution
Initial Access
View detailed technique mapping

References

https://github.com/chamilo/chamilo-lms/security/advisories/GHSA-273p-jw9w-3g22
github.com
https://github.com/chamilo/chamilo-lms/commit/7c4965e48769d1d06413836429e386816a465c7f
github.com
https://github.com/chamilo/chamilo-lms/commit/da671d66a146887be3a16eabc5dcf0a92c55f7da
github.com
and 1 more references View all →

Timeline

Published
Apr 14, 2026
Last Updated
Apr 23, 2026

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