# CVE-2020-6988: Information disclosure in Rockwell Automation MicroLogix 1400 Controllers Series B v21.001 and prior, Series A, all versions, MicroLogix 1100 Controller, all versions, RSLogix 500 Software v12.001 and prior

> Remote attackers can exploit authentication flaws in Rockwell MicroLogix controllers to leak credentials and bypass security controls.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Mar 2020
- **Updated:** 3 Jun 2026
- **Also known as:** GHSA-8v4g-559x-qqxm

## What is CVE-2020-6988?

CVE-2020-6988 is a high-severity vulnerability in Rockwell Automation MicroLogix 1400 Controllers Series B v21.001 and prior, Series A, all versions, MicroLogix 1100 Controller, all versions, RSLogix 500 Software v12.001 and prior, published on 16 Mar 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Rockwell Automation MicroLogix 1400 Controllers Series B v21.001 and prior, Series A, all versions, MicroLogix 1100 Controller, all versions, RSLogix 500 Software v12.001 and prior, A remote, unauthenticated attacker can send a request from the RSLogix 500 software to the victim’s MicroLogix controller. The controller will then respond to the client with used password values to authenticate the user on the client-side. This method of authentication may allow an attacker to bypass authentication altogether, disclose sensitive information, or leak credentials.

Weakness: CWE-287 (Improper Authentication), CWE-603 (Use of Client-Side Authentication)

## Which versions are affected by CVE-2020-6988?

It affects 4 products.


Products: Rockwellautomation Micrologix 1100 Firmware, Rockwellautomation Micrologix 1400 a Firmware, Rockwellautomation Micrologix 1400 B Firmware, Rockwellautomation Rslogix 500.

## How do I fix CVE-2020-6988?

No fix has been published for CVE-2020-6988 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-6988 being exploited?

There is no known exploitation of CVE-2020-6988 in the wild and no public exploit code.

## Other vulnerabilities in Rockwell Automation MicroLogix 1400 Controllers Series B v21.001 and prior, Series A, all versions, MicroLogix 1100 Controller, all versions, RSLogix 500 Software v12.001 and prior

- [CVE-2020-6984](https://insights.sbomify.com/CVE-2020-6984/): Weak cryptography in Rockwell Automation MicroLogix 1400 Controllers Series B v21.001 and prior, Series A, all versions, MicroLogix 1100 Controller, all versions, RSLogix 500 Software v12.001 and prior (critical 9.8)
- [CVE-2020-6990](https://insights.sbomify.com/CVE-2020-6990/): Hardcoded credentials in Rockwell Automation MicroLogix 1400 Controllers Series B v21.001 and prior, Series A, all versions, MicroLogix 1100 Controller, all versions, RSLogix 500 Software v12.001 and prior (critical 9.8)
- [CVE-2015-6490](https://insights.sbomify.com/CVE-2015-6490/): Memory corruption in n/a (critical 9.8)
- [CVE-2022-3166](https://insights.sbomify.com/CVE-2022-3166/): MicroLogix 1100 & 1400 Product Web Server Application Vulnerable to Denial-Of-Service Condition Attack (high 7.5)
- [CVE-2021-33012](https://insights.sbomify.com/CVE-2021-33012/): Denial of service in Rockwell Automation MicroLogix 1100 (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-6988 and fix it if it is affected.

What it is: CVE-2020-6988 is a high-severity vulnerability in Rockwell Automation MicroLogix 1400 Controllers Series B v21.001 and prior, Series A, all versions, MicroLogix 1100 Controller, all versions, RSLogix 500 Software v12.001 and prior, published on 16 Mar 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-2020-6988 in the wild and no public exploit code.

Affected product: Rockwell Automation MicroLogix 1400 Controllers Series B v21.001 and prior, Series A, all versions, MicroLogix 1100 Controller, all versions, RSLogix 500 Software v12.001 and prior. 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-2020-6988/ (Markdown: https://insights.sbomify.com/CVE-2020-6988/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-6988
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-6988
- OSV: https://osv.dev/vulnerability/CVE-2020-6988

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-6988/
Summaries are generated and may contain mistakes; the official description above is the record.