# CVE-2021-43928: Command injection in Mail Station

> Remote authenticated users can execute arbitrary OS commands in Synology Mail Station via improper neutralization of special elements.

- **Severity:** Critical 9.9 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **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:** 7 Feb 2022
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-xcmm-3w7w-cqq9

## What is CVE-2021-43928?

CVE-2021-43928 is a critical command injection vulnerability in Synology Mail Station, published on 7 Feb 2022. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Improper neutralization of special elements used in an OS command ('OS Command Injection') vulnerability in mail sending and receiving component in Synology Mail Station before 20211105-10315 allows remote authenticated users to execute arbitrary commands via unspecified vectors.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2021-43928?

It affects 1 product.


Products: Synology Mail Station.

## How do I fix CVE-2021-43928?

No fix has been published for CVE-2021-43928 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-43928 being exploited?

There is no known exploitation of CVE-2021-43928 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43928 and fix it if it is affected.

What it is: CVE-2021-43928 is a critical command injection vulnerability in Synology Mail Station, published on 7 Feb 2022. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-43928 in the wild and no public exploit code.

Affected product: Synology Mail Station. 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-2021-43928/ (Markdown: https://insights.sbomify.com/CVE-2021-43928/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43928
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43928
- OSV: https://osv.dev/vulnerability/CVE-2021-43928

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43928/
Summaries are generated and may contain mistakes; the official description above is the record.