# CVE-2020-6111: Denial of service in Allen-Bradley

> An attacker can cause a denial of service on Allen-Bradley MicroLogix 1100 PLCs by sending a specially crafted packet.

- **Severity:** High 7.5 (`CVSS:3.0/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:** 3 Dec 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-43vh-m5cv-9pgr

## What is CVE-2020-6111?

CVE-2020-6111 is a high-severity denial of service vulnerability in Allen-Bradley, published on 3 Dec 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An exploitable denial-of-service vulnerability exists in the IPv4 functionality of Allen-Bradley MicroLogix 1100 Programmable Logic Controller Systems Series B FRN 16.000, Series B FRN 15.002, Series B FRN 15.000, Series B FRN 14.000, Series B FRN 13.000, Series B FRN 12.000, Series B FRN 11.000 and Series B FRN 10.000. A specially crafted packet can cause a major error, resulting in a denial of service. An attacker can send a malicious packet to trigger this vulnerability.

Weakness: CWE-189

## Which versions are affected by CVE-2020-6111?

It affects 1 product.


Products: Rockwellautomation Micrologix 1100 B Firmware.

## How do I fix CVE-2020-6111?

No fix has been published for CVE-2020-6111 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-6111 being exploited?

There is no known exploitation of CVE-2020-6111 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-6111 and fix it if it is affected.

What it is: CVE-2020-6111 is a high-severity denial of service vulnerability in Allen-Bradley, published on 3 Dec 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-2020-6111 in the wild and no public exploit code.

Affected product: Allen-Bradley. 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-2020-6111/ (Markdown: https://insights.sbomify.com/CVE-2020-6111/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-6111
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-6111
- OSV: https://osv.dev/vulnerability/CVE-2020-6111

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-6111/
Summaries are generated and may contain mistakes; the official description above is the record.