# CVE-2019-5166: Memory corruption in WAGO PFC200 Firmware

> A stack buffer overflow in the WAGO PFC 200 iocheckd service allows remote code execution via a crafted XML cache file.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Mar 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-w4qg-v526-9gvf

## What is CVE-2019-5166?

CVE-2019-5166 is a high-severity memory corruption vulnerability in WAGO PFC200 Firmware, published on 10 Mar 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An exploitable stack buffer overflow vulnerability exists in the iocheckd service ‘I/O-Check’ functionality of WAGO PFC 200 version 03.02.02(14). A specially crafted XML cache file written to a specific location on the device can cause a stack buffer overflow, resulting in code execution. An attacker can send a specially crafted packet to trigger the parsing of this cache file.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2019-5166?

It affects 1 product.


Products: Wago Pfc200 Firmware.

## How do I fix CVE-2019-5166?

No fix has been published for CVE-2019-5166 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-5166 being exploited?

There is no known exploitation of CVE-2019-5166 in the wild and no public exploit code.

## Other vulnerabilities in WAGO PFC200 Firmware

- [CVE-2018-5459](https://insights.sbomify.com/CVE-2018-5459/): Auth bypass in WAGO PFC200 Series (critical 9.8)
- [CVE-2019-5160](https://insights.sbomify.com/CVE-2019-5160/): Server-side request forgery in WAGO PFC200 Firmware (critical 9.1)
- [CVE-2019-5161](https://insights.sbomify.com/CVE-2019-5161/): Code injection in WAGO PFC200 Firmware (critical 9.1)
- [CVE-2019-5184](https://insights.sbomify.com/CVE-2019-5184/): Use after free in Wago (high 7.8)
- [CVE-2019-5169](https://insights.sbomify.com/CVE-2019-5169/): Command injection in WAGO PFC200 (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-5166 and fix it if it is affected.

What it is: CVE-2019-5166 is a high-severity memory corruption vulnerability in WAGO PFC200 Firmware, published on 10 Mar 2020. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-5166 in the wild and no public exploit code.

Affected product: WAGO PFC200 Firmware. 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-2019-5166/ (Markdown: https://insights.sbomify.com/CVE-2019-5166/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-5166
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-5166
- OSV: https://osv.dev/vulnerability/CVE-2019-5166

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-5166/
Summaries are generated and may contain mistakes; the official description above is the record.