# CVE-2021-20986: Hilscher: Denial of Service vulnerability in PROFINET IO Device

> Attackers can cause loss of cyclic or interruption of acyclic communication in Hilscher PROFINET IO Devices, disrupting industrial operations.

- **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:** 16 Feb 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-4p8g-xcvq-m8r7

## What is CVE-2021-20986?

CVE-2021-20986 is a high-severity denial of service vulnerability in Hilscher OHV, published on 16 Feb 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A Denial of Service vulnerability was found in Hilscher PROFINET IO Device V3 in versions prior to V3.14.0.7. This may lead to unexpected loss of cyclic communication or interruption of acyclic communication.

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

## Which versions are affected by CVE-2021-20986?

It affects 24 products.


Products: Hilscher Profinet Io Device Firmware, Pepperl-Fuchs Ohv-F230-B17 Firmware, Pepperl-Fuchs Oit500-F113b17-Cb Firmware, Pepperl-Fuchs Pcv100-F200-B17-V1d-6011-6997 Firmware, Pepperl-Fuchs Pcv100-F200-B17-V1d-6011-8203 Firmware, Pepperl-Fuchs Pcv100-F200-B17-V1d-6011 Firmware, Pepperl-Fuchs Pcv100-F200-B17-V1d Firmware, Pepperl-Fuchs Pcv50-F200-B17-V1d Firmware, Pepperl-Fuchs Pcv80-F200-B17-V1d Firmware, Pepperl-Fuchs Pgv100-F200-B17-V1d-7477 Firmware, Pepperl-Fuchs Pgv100-F200a-B17-V1d Firmware, Pepperl-Fuchs Pgv100a-F200-B28-V1d Firmware, Pepperl-Fuchs Pgv100a-F200a-B28-V1d Firmware, Pepperl-Fuchs Pgv100aq-F200-B28-V1d Firmware, Pepperl-Fuchs Pgv100aq-F200a-B28-V1d Firmware, Pepperl-Fuchs Pgv150i-F200a-B17-V1d Firmware, Pepperl-Fuchs Pha Firmware, Pepperl-Fuchs Pxv100-F200-B17-V1d-3636 Firmware, Pepperl-Fuchs Pxv100-F200-B17-V1d Firmware, Pepperl-Fuchs Pxv100a-F200-B28-V1d-6011 Firmware and 4 more.

## How do I fix CVE-2021-20986?

No fix has been published for CVE-2021-20986 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-20986 being exploited?

There is no known exploitation of CVE-2021-20986 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20986 and fix it if it is affected.

What it is: CVE-2021-20986 is a high-severity denial of service vulnerability in Hilscher OHV, published on 16 Feb 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-2021-20986 in the wild and no public exploit code.

Affected product: Hilscher OHV. 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-2021-20986/ (Markdown: https://insights.sbomify.com/CVE-2021-20986/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20986
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20986
- OSV: https://osv.dev/vulnerability/CVE-2021-20986

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-20986/
Summaries are generated and may contain mistakes; the official description above is the record.