# CVE-2023-2020: Unauthorized scheduling of downtimes via REST API

> Unauthorized users can schedule downtimes for any host via the REST API due to insufficient permission checks in Checkmk.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/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:** 18 Apr 2023
- **Updated:** 5 Feb 2025
- **Also known as:** GHSA-w7j6-p4c4-j78m, UBUNTU-CVE-2023-2020

## What is CVE-2023-2020?

CVE-2023-2020 is a medium-severity missing authorization vulnerability in Checkmk Checkmk, published on 18 Apr 2023. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Insufficient permission checks in the REST API in Tribe29 Checkmk <= 2.1.0p27 and <= 2.2.0b4 (beta) allow unauthorized users to schedule downtimes for any host.

Weakness: CWE-863 (Incorrect Authorization), CWE-280 (Improper Handling of Insufficient Permissions or Privileges)

## Which versions are affected by CVE-2023-2020?

It affects 1 product.


Products: Checkmk Checkmk.

## How do I fix CVE-2023-2020?

No fix has been published for CVE-2023-2020 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-2020 being exploited?

There is no known exploitation of CVE-2023-2020 in the wild and no public exploit code.

## Other vulnerabilities in Checkmk Checkmk

- [CVE-2025-39666](https://insights.sbomify.com/CVE-2025-39666/): omd: Local privilege escalation when executing omd commands as root (critical 9.3)
- [CVE-2024-8606](https://insights.sbomify.com/CVE-2024-8606/): Fix 2FA bypass via RestAPI (critical 9.2)
- [CVE-2022-46836](https://insights.sbomify.com/CVE-2022-46836/): PHP code injection in watolib (critical 9.1)
- [CVE-2025-32919](https://insights.sbomify.com/CVE-2025-32919/): Privilege Escalation in Windows License plugin for Checkmk Windows Agent (high 8.8)
- [CVE-2024-28827](https://insights.sbomify.com/CVE-2024-28827/): Privilege escalation in Windows agent (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-2020 and fix it if it is affected.

What it is: CVE-2023-2020 is a medium-severity missing authorization vulnerability in Checkmk Checkmk, published on 18 Apr 2023. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-2020 in the wild and no public exploit code.

Affected product: Checkmk Checkmk. 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-2023-2020/ (Markdown: https://insights.sbomify.com/CVE-2023-2020/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-2020
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-2020
- OSV: https://osv.dev/vulnerability/CVE-2023-2020

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-2020/
Summaries are generated and may contain mistakes; the official description above is the record.