# CVE-2018-7833: Denial of service in Embedded Web Servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200

> Unauthenticated attackers can crash the embedded web server in Schneider Electric PLCs by sending specially crafted XML data.

- **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:** 17 Dec 2018
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-46rq-v233-vjx5

## What is CVE-2018-7833?

CVE-2018-7833 is a high-severity denial of service vulnerability in Schneider Electric SE Embedded Web Servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200, published on 17 Dec 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An Improper Check for Unusual or Exceptional Conditions vulnerability exists in the embedded web servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200 where an unauthenticated user can send a specially crafted XML data via a POST request to cause the web server to become unavailable

Weakness: CWE-754 (Improper Check for Unusual or Exceptional Conditions)

## Which versions are affected by CVE-2018-7833?

It affects 4 products.


Products: Schneider-Electric Modicom Bmxnor0200h Firmware, Schneider-Electric Modicom M340 Firmware, Schneider-Electric Modicom Premium Firmware, Schneider-Electric Modicom Quantum Firmware.

## How do I fix CVE-2018-7833?

No fix has been published for CVE-2018-7833 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-7833 being exploited?

There is no known exploitation of CVE-2018-7833 in the wild and no public exploit code.

## Other vulnerabilities in Schneider Electric SE Embedded Web Servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200

- [CVE-2018-7809](https://insights.sbomify.com/CVE-2018-7809/): Auth bypass in Embedded Web Servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200 (critical 9.8)
- [CVE-2018-7811](https://insights.sbomify.com/CVE-2018-7811/): Auth bypass in Embedded Web Servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200 (critical 9.8)
- [CVE-2018-7831](https://insights.sbomify.com/CVE-2018-7831/): Cross-site scripting in Embedded Web Servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200 (high 8.8)
- [CVE-2018-7812](https://insights.sbomify.com/CVE-2018-7812/): Information disclosure in Embedded Web Servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200 (high 7.5)
- [CVE-2018-7830](https://insights.sbomify.com/CVE-2018-7830/): Other in Embedded Web Servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200 (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-7833 and fix it if it is affected.

What it is: CVE-2018-7833 is a high-severity denial of service vulnerability in Schneider Electric SE Embedded Web Servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200, published on 17 Dec 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-2018-7833 in the wild and no public exploit code.

Affected product: Schneider Electric SE Embedded Web Servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200. 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-2018-7833/ (Markdown: https://insights.sbomify.com/CVE-2018-7833/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-7833
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-7833
- OSV: https://osv.dev/vulnerability/CVE-2018-7833

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From sbomify Insights: https://insights.sbomify.com/CVE-2018-7833/
Summaries are generated and may contain mistakes; the official description above is the record.