# CVE-2020-6998: Rockwell Automation CompactLogix 5370 and ControlLogix 5570 Controllers Improper Input Validation

> Attackers can cause denial of service in Rockwell Automation PLCs by sending crafted CIP packets that trigger an infinite loop during connection establishment.

- **Severity:** Medium 5.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Jul 2022
- **Updated:** 17 Apr 2025
- **Also known as:** GHSA-9r87-pc5m-9w97

## What is CVE-2020-6998?

CVE-2020-6998 is a medium-severity denial of service vulnerability in Rockwell Automation Armor Compact GuardLogix 5370 controllers, published on 27 Jul 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The connection establishment algorithm found in Rockwell Automation CompactLogix 5370 and ControlLogix 5570 versions 33 and prior does not sufficiently manage its control flow during execution, creating an infinite loop. This may allow an attacker to send specially crafted CIP packet requests to a controller, which may cause denial-of-service conditions in communications with other products.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2020-6998?

It affects 9 products.


Products: Rockwellautomation Armor Compact Guardlogix 5370 Firmware, Rockwellautomation Compact Guardlogix 5370 Firmware, Rockwellautomation Compactlogix 5370 L1 Firmware, Rockwellautomation Compactlogix 5370 L2 Firmware, Rockwellautomation Compactlogix 5370 L3 Firmware, Rockwellautomation Controllogix 5570 Firmware, Rockwellautomation Guardlogix 5560 Firmware, Rockwellautomation Guardlogix 5570 Firmware, Rockwellautomation Guardlogix 5580 Firmware.

## How do I fix CVE-2020-6998?

No fix has been published for CVE-2020-6998 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-6998 being exploited?

There is no known exploitation of CVE-2020-6998 in the wild and no public exploit code.

## Other vulnerabilities in Rockwell Automation Armor Compact GuardLogix 5370 controllers

- [CVE-2019-10952](https://insights.sbomify.com/CVE-2019-10952/): Rockwell Automation CompactLogix 5370 Uncontrolled Resource Consumption (critical 9.8)
- [CVE-2019-10954](https://insights.sbomify.com/CVE-2019-10954/): Rockwell Automation CompactLogix 5370 Stack-based Buffer Overflow (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-6998 and fix it if it is affected.

What it is: CVE-2020-6998 is a medium-severity denial of service vulnerability in Rockwell Automation Armor Compact GuardLogix 5370 controllers, published on 27 Jul 2022. 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-2020-6998 in the wild and no public exploit code.

Affected product: Rockwell Automation Armor Compact GuardLogix 5370 controllers. 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-2020-6998/ (Markdown: https://insights.sbomify.com/CVE-2020-6998/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-6998
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-6998
- OSV: https://osv.dev/vulnerability/CVE-2020-6998

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-6998/
Summaries are generated and may contain mistakes; the official description above is the record.