# CVE-2018-16994: Denial of service in n/a

> Remote attackers can cause a complete lockup of Phoenix Contact and Bosch Rexroth fieldbus couplers by sending requests with non-standard symbols, requiring no authentication.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 18 Feb 2020
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-fjq9-2cmr-75cm

## What is CVE-2018-16994?

CVE-2018-16994 is a high-severity denial of service vulnerability in n/a, published on 18 Feb 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered on PHOENIX CONTACT AXL F BK PN <=1.0.4, AXL F BK ETH <= 1.12, and AXL F BK ETH XC <= 1.11 devices and Bosch Rexroth S20-ETH-BK and Rexroth S20-PN-BK+ (the S20-PN-BK+/S20-ETH-BK fieldbus couplers sold by Bosch Rexroth contain technology from Phoenix Contact). Incorrect handling of a request with non-standard symbols allows remote attackers to initiate a complete lock up of the bus coupler. Authentication of the request is not required.

## Which versions are affected by CVE-2018-16994?

It affects 3 products.


Products: Phoenixcontact Axl F Bk Eth Firmware, Phoenixcontact Axl F Bk Eth Xc Firmware, Phoenixcontact Axl F Bk Pn Firmware.

## How do I fix CVE-2018-16994?

No fix has been published for CVE-2018-16994 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-16994 being exploited?

There is no known exploitation of CVE-2018-16994 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-16994 and fix it if it is affected.

What it is: CVE-2018-16994 is a high-severity denial of service vulnerability in n/a, published on 18 Feb 2020. 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-2018-16994 in the wild and no public exploit code.

Affected product: n/a. 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-2018-16994/ (Markdown: https://insights.sbomify.com/CVE-2018-16994/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-16994
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-16994
- OSV: https://osv.dev/vulnerability/CVE-2018-16994

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-16994/
Summaries are generated and may contain mistakes; the official description above is the record.