# CVE-2021-33719: Memory corruption in SIPROTEC 5 relays with CPU variants CP050

> Attackers can cause denial of service or remote code execution on SIPROTEC 5 relays by sending crafted packets to port 4443.

- **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:** 14 Sep 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-6936-h7xw-gfq3

## What is CVE-2021-33719?

CVE-2021-33719 is a critical memory corruption vulnerability in Siemens SIPROTEC 5 relays with CPU variants CP050, published on 14 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability has been identified in SIPROTEC 5 relays with CPU variants CP050 (All versions < V8.80), SIPROTEC 5 relays with CPU variants CP100 (All versions < V8.80), SIPROTEC 5 relays with CPU variants CP300 (All versions < V8.80). Specially crafted packets sent to port 4443/tcp could cause a Denial-of-Service condition or potential remote code execution.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2021-33719?

It affects 3 products.


Products: Siemens Siprotec 5 With Cpu Variant Cp050, Siemens Siprotec 5 With Cpu Variant Cp100, Siemens Siprotec 5 With Cpu Variant Cp300.

## How do I fix CVE-2021-33719?

No fix has been published for CVE-2021-33719 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-33719 being exploited?

There is no known exploitation of CVE-2021-33719 in the wild and no public exploit code.

## Other vulnerabilities in Siemens SIPROTEC 5 relays with CPU variants CP050

- [CVE-2021-33720](https://insights.sbomify.com/CVE-2021-33720/): Denial of service in SIPROTEC 5 relays with CPU variants CP050 (high 7.5)
- [CVE-2021-37206](https://insights.sbomify.com/CVE-2021-37206/): Denial of service in SIPROTEC 5 relays with CPU variants CP050 (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-33719 and fix it if it is affected.

What it is: CVE-2021-33719 is a critical memory corruption vulnerability in Siemens SIPROTEC 5 relays with CPU variants CP050, published on 14 Sep 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-2021-33719 in the wild and no public exploit code.

Affected product: Siemens SIPROTEC 5 relays with CPU variants CP050. 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-2021-33719/ (Markdown: https://insights.sbomify.com/CVE-2021-33719/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-33719
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-33719
- OSV: https://osv.dev/vulnerability/CVE-2021-33719

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-33719/
Summaries are generated and may contain mistakes; the official description above is the record.