Auth bypass in Chamilo Chamilo-Lms

CVE-2026-34602

Chamilo LMS is an open-source learning management system. In versions prior to 2.0.0-RC.3, the /api/course_rel_users endpoint is vulnerable to Insecure Direct Object Reference (IDOR), allowing an authenticated attacker to modify the user parameter in the request body to enroll any arbitrary user into any course without proper authorization checks. The backend trusts the user-supplied input for the user field and performs no server-side verification that the requester owns the referenced user ID or has permission to act on behalf of other users. This enables unauthorized manipulation of user-course relationships, potentially granting unintended access to course materials, bypassing enrollment controls, and compromising platform integrity. This issue has been fixed in version 2.0.0-RC.3.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N.

EPSS exploit prediction

EPSS: 0.004 (27.1th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 27th percentile — 27.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-34602: held from 0.002 to 0.004.

EPSS over last 30 days · oldest: 0.002 · newest: 0.004 · change: +0.002

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-34602?
CVE-2026-34602 is a high-severity vulnerability in Chamilo Chamilo-Lms, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 7.1/10. Published 2026-04-14.
How severe is CVE-2026-34602?
High severity. CVSS v3 base score is 7.1 out of 10.