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

> Authenticated attackers can enroll arbitrary users into courses via IDOR in the API, bypassing enrollment controls and compromising platform integrity.

- **Severity:** High 7.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Apr 2026
- **Updated:** 15 Apr 2026
- **Also known as:** GHSA-x373-8j9j-g5pj

## What is CVE-2026-34602?

CVE-2026-34602 is a high-severity missing authorization vulnerability in Chamilo Chamilo Lms, published on 14 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official 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.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-34602?

It affects 1 product.


Products: Chamilo Chamilo Lms.

## How do I fix CVE-2026-34602?

No fix has been published for CVE-2026-34602 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-34602 being exploited?

There is no known exploitation of CVE-2026-34602 in the wild and no public exploit code.

## Other vulnerabilities in Chamilo Chamilo Lms

- [CVE-2025-50187](https://insights.sbomify.com/CVE-2025-50187/): Chamilo: Evaluation of untrusted user input leads to Remote Code Execution (critical 9.8)
- [CVE-2023-34944](https://insights.sbomify.com/CVE-2023-34944/): File upload in n/a (critical 9.8)
- [CVE-2022-27423](https://insights.sbomify.com/CVE-2022-27423/): SQL injection in n/a (critical 9.8)
- [CVE-2021-35414](https://insights.sbomify.com/CVE-2021-35414/): SQL injection in n/a (critical 9.8)
- [CVE-2019-13082](https://insights.sbomify.com/CVE-2019-13082/): File upload in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34602 and fix it if it is affected.

What it is: CVE-2026-34602 is a high-severity missing authorization vulnerability in Chamilo Chamilo Lms, published on 14 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-34602 in the wild and no public exploit code.

Affected product: Chamilo Chamilo Lms. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-34602/ (Markdown: https://insights.sbomify.com/CVE-2026-34602/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34602
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34602
- OSV: https://osv.dev/vulnerability/CVE-2026-34602

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-34602/
Summaries are generated and may contain mistakes; the official description above is the record.