# CVE-2021-27388: Missing authorization in SINAMICS Medium Voltage Products, Remote Access

> Unauthenticated attackers can cause denial of service or modify configuration and control commands in SINAMICS Medium Voltage products via Sm@rtServer.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Jun 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-78x7-234w-r2hv

## What is CVE-2021-27388?

CVE-2021-27388 is a critical missing authorization vulnerability in SINAMICS Medium Voltage Products, Remote Access, published on 15 Jun 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

SINAMICS medium voltage routable products are affected by a vulnerability in the Sm@rtServer component for remote access that could allow an unauthenticated attacker to cause a denial-of-service condition, and/or execution of limited configuration modifications and/or execution of limited control commands on the SINAMICS Medium Voltage Products, Remote Access (SINAMICS SL150: All versions, SINAMICS SM150: All versions, SINAMICS SM150i: All versions).

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-27388?

It affects 3 products.


Products: Siemens Sinamics Sl150 Firmware, Siemens Sinamics Sm150 Firmware, Siemens Sinamics Sm150i Firmware.

## How do I fix CVE-2021-27388?

No fix has been published for CVE-2021-27388 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-27388 being exploited?

There is no known exploitation of CVE-2021-27388 in the wild and no public exploit code.

## Other vulnerabilities in SINAMICS Medium Voltage Products, Remote Access

- [CVE-2021-31337](https://insights.sbomify.com/CVE-2021-31337/): Missing authorization in SINAMICS Medium Voltage Products (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-27388 and fix it if it is affected.

What it is: CVE-2021-27388 is a critical missing authorization vulnerability in SINAMICS Medium Voltage Products, Remote Access, published on 15 Jun 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-27388 in the wild and no public exploit code.

Affected product: SINAMICS Medium Voltage Products, Remote Access. 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-2021-27388/ (Markdown: https://insights.sbomify.com/CVE-2021-27388/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27388
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27388
- OSV: https://osv.dev/vulnerability/CVE-2021-27388

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-27388/
Summaries are generated and may contain mistakes; the official description above is the record.