# CVE-2023-4420: Information disclosure in LMS5xx

> Remote attackers can intercept and manipulate unencrypted communication with SICK LMS5xx sensors, leading to sensitive data disclosure and integrity loss.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 24 Aug 2023
- **Updated:** 1 Jun 2026
- **Also known as:** GHSA-f3xg-jgh3-jw7h

## What is CVE-2023-4420?

CVE-2023-4420 is a critical vulnerability in SICK AG LMS5xx, published on 24 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A remote unprivileged attacker can intercept the communication via e.g. Man-In-The-Middle, due to the absence of Transport Layer Security (TLS) in the SICK LMS5xx. This lack of encryption in the communication channel can lead to the unauthorized disclosure of sensitive information. The attacker can exploit this weakness to eavesdrop on the communication between the LMS5xx and the Client, and potentially manipulate the data being transmitted.

Weakness: CWE-311 (Missing Encryption of Sensitive Data)

## Which versions are affected by CVE-2023-4420?

It affects 3 products.


Products: Sick Lms500 Firmware, Sick Lms511 Firmware, Sick Lms531 Firmware.

## How do I fix CVE-2023-4420?

No fix has been published for CVE-2023-4420 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-4420 being exploited?

There is no known exploitation of CVE-2023-4420 in the wild and no public exploit code.

## Other vulnerabilities in SICK AG LMS5xx

- [CVE-2023-4419](https://insights.sbomify.com/CVE-2023-4419/): Hardcoded credentials in LMS5xx (critical 9.8)
- [CVE-2023-31412](https://insights.sbomify.com/CVE-2023-31412/): Weak cryptography in LMS5xx (high 7.5)
- [CVE-2023-4418](https://insights.sbomify.com/CVE-2023-4418/): Denial of service in LMS5xx (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-4420 and fix it if it is affected.

What it is: CVE-2023-4420 is a critical vulnerability in SICK AG LMS5xx, published on 24 Aug 2023. 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-2023-4420 in the wild and no public exploit code.

Affected product: SICK AG LMS5xx. 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-2023-4420/ (Markdown: https://insights.sbomify.com/CVE-2023-4420/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-4420
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-4420
- OSV: https://osv.dev/vulnerability/CVE-2023-4420

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-4420/
Summaries are generated and may contain mistakes; the official description above is the record.