# CVE-2018-14821: Denial of service in RSLinx Classic

> Remote unauthenticated attackers can crash RSLinx Classic by sending malformed CIP packets, requiring manual restart to restore service.

- **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:** 20 Sep 2018
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-g2xj-449r-g2rx

## What is CVE-2018-14821?

CVE-2018-14821 is a high-severity denial of service vulnerability in Rockwell Automation RSLinx Classic, published on 20 Sep 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Rockwell Automation RSLinx Classic Versions 4.00.01 and prior. This vulnerability may allow a remote, unauthenticated threat actor to intentionally send a malformed CIP packet to Port 44818, causing the RSLinx Classic application to terminate. The user will need to manually restart the software to regain functionality.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2018-14821?

It affects 1 product.


Products: Rockwellautomation Rslinx.

## How do I fix CVE-2018-14821?

No fix has been published for CVE-2018-14821 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-14821 being exploited?

There is no known exploitation of CVE-2018-14821 in the wild and no public exploit code.

## Other vulnerabilities in Rockwell Automation RSLinx Classic

- [CVE-2019-6553](https://insights.sbomify.com/CVE-2019-6553/): Memory corruption in RSLinx Classic (critical 9.8)
- [CVE-2018-14829](https://insights.sbomify.com/CVE-2018-14829/): Memory corruption in RSLinx Classic (critical 9.8)
- [CVE-2020-13573](https://insights.sbomify.com/CVE-2020-13573/): Denial of service in Rockwell Automation (high 7.5)
- [CVE-2018-14827](https://insights.sbomify.com/CVE-2018-14827/): Denial of service in RSLinx Classic (high 7.5)
- [CVE-2014-9204](https://insights.sbomify.com/CVE-2014-9204/): Memory corruption in n/a (medium 6.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-14821 and fix it if it is affected.

What it is: CVE-2018-14821 is a high-severity denial of service vulnerability in Rockwell Automation RSLinx Classic, published on 20 Sep 2018. 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-2018-14821 in the wild and no public exploit code.

Affected product: Rockwell Automation RSLinx Classic. 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-2018-14821/ (Markdown: https://insights.sbomify.com/CVE-2018-14821/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-14821
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-14821
- OSV: https://osv.dev/vulnerability/CVE-2018-14821

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-14821/
Summaries are generated and may contain mistakes; the official description above is the record.