# CVE-2020-5239: Unspecified vulnerability in the fetchmail script in Mailu

> An authenticated user can exploit a fetchmail script vulnerability to gain full administrative access to the Mailu mail server instance.

- **Severity:** High 8.7 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 13 Feb 2020
- **Updated:** 4 Aug 2024

## What is CVE-2020-5239?

CVE-2020-5239 is a high-severity vulnerability in Mailu, published on 13 Feb 2020. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

In Mailu before version 1.7, an authenticated user can exploit a vulnerability in Mailu fetchmail script and gain full access to a Mailu instance. Mailu servers that have open registration or untrusted users are most impacted. The master and 1.7 branches are patched on our git repository. All Docker images published on docker.io/mailu for tags 1.5, 1.6, 1.7 and master are patched. For detailed instructions about patching and securing the server afterwards, see https://github.com/Mailu/Mailu/issues/1354

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2020-5239?

It affects 1 product.


Products: Mailu Mailu.

## How do I fix CVE-2020-5239?

No fix has been published for CVE-2020-5239 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-5239 being exploited?

There is no known exploitation of CVE-2020-5239 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-5239 and fix it if it is affected.

What it is: CVE-2020-5239 is a high-severity vulnerability in Mailu, published on 13 Feb 2020. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2020-5239 in the wild and no public exploit code.

Affected product: Mailu. 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-2020-5239/ (Markdown: https://insights.sbomify.com/CVE-2020-5239/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-5239
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-5239
- OSV: https://osv.dev/vulnerability/CVE-2020-5239

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-5239/
Summaries are generated and may contain mistakes; the official description above is the record.