# CVE-2020-7549: Denial of service in Web Server on Modicon M340, Legacy Offers Modicon Quantum and Modicon Premium and associated Communication Modules (see security notification for affected versions)

> Attackers can cause denial of HTTP and FTP services on Modicon PLCs by sending specially crafted requests to the web server.

- **Severity:** High 7.5 (`CVSS:3.1/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:** 11 Dec 2020
- **Updated:** 28 May 2026
- **Also known as:** GHSA-mg3m-w94w-vr47

## What is CVE-2020-7549?

CVE-2020-7549 is a high-severity denial of service vulnerability in Web Server on Modicon M340, Legacy Offers Modicon Quantum and Modicon Premium and associated Communication Modules (see security notification for affected versions), published on 11 Dec 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A CWE-754: Improper Check for Unusual or Exceptional Conditions vulnerability exists in the Web Server on Modicon M340, Legacy Offers Modicon Quantum and Modicon Premium and associated Communication Modules (see security notification for affected versions), that could cause denial of HTTP and FTP services when a series of specially crafted requests is sent to the controller over HTTP.

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

## Which versions are affected by CVE-2020-7549?

It affects 19 products.


Products: Schneider-Electric 140cpu65150 Firmware, Schneider-Electric 140noc78000 Firmware, Schneider-Electric 140noc78100 Firmware, Schneider-Electric 140noe77111 Firmware, Schneider-Electric Bmxnoc0401 Firmware, Schneider-Electric Bmxnoe0100 Firmware, Schneider-Electric Bmxnoe0110 Firmware, Schneider-Electric Modicon M340 Bmxp341000 Firmware, Schneider-Electric Modicon M340 Bmxp342000 Firmware, Schneider-Electric Modicon M340 Bmxp3420102 Firmware, Schneider-Electric Modicon M340 Bmxp3420102cl Firmware, Schneider-Electric Modicon M340 Bmxp342020 Firmware, Schneider-Electric Modicon M340 Bmxp3420302 Firmware, Schneider-Electric Modicon M340 Bmxp3420302cl Firmware, Schneider-Electric Tsxety4103 Firmware, Schneider-Electric Tsxety5103 Firmware, Schneider-Electric Tsxp574634 Firmware, Schneider-Electric Tsxp575634 Firmware, Schneider-Electric Tsxp576634 Firmware.

## How do I fix CVE-2020-7549?

No fix has been published for CVE-2020-7549 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-7549 being exploited?

There is no known exploitation of CVE-2020-7549 in the wild and no public exploit code.

## Other vulnerabilities in Web Server on Modicon M340, Legacy Offers Modicon Quantum and Modicon Premium and associated Communication Modules (see security notification for affected versions)

- [CVE-2020-7540](https://insights.sbomify.com/CVE-2020-7540/): Missing authorization in Web Server on Modicon M340, Legacy Offers Modicon Quantum and Modicon Premium and associated Communication Modules (see security notification for affected versions) (critical 9.8)
- [CVE-2021-22785](https://insights.sbomify.com/CVE-2021-22785/): Information disclosure in Modicon M340 CPUs: BMXP34 (Versions prior to V3.40), Modicon M340 X80 Ethernet Communication Modules: BMXNOE0100 (H), BMXNOE0110 (H), BMXNOC0401, BMXNOR0200H RTU (All Versions), Modicon Premium Processors with integrated Ethernet (Copro): TSXP574634, TSXP575634, TSXP576634 (All Versions), Modicon Quantum Processors with Integrated Ethernet (Copro): 140CPU65xxxxx (All Versions), Modicon Quantum Communication Modules: 140NOE771x1, 140NOC78x00, 140NOC77101 (All Versions), Modicon Premium Communication Modules: TSXETY4103, TSXETY5103 (All Versions) (high 7.5)
- [CVE-2021-22787](https://insights.sbomify.com/CVE-2021-22787/): Denial of service in Modicon M340 CPUs: BMXP34 (Versions prior to V3.40), Modicon M340 X80 Ethernet Communication Modules: BMXNOE0100 (H), BMXNOE0110 (H), BMXNOC0401, BMXNOR0200H RTU (All Versions), Modicon Premium Processors with integrated Ethernet (Copro): TSXP574634, TSXP575634, TSXP576634 (All Versions), Modicon Quantum Processors with Integrated Ethernet (Copro): 140CPU65xxxxx (All Versions), Modicon Quantum Communication Modules: 140NOE771x1, 140NOC78x00, 140NOC77101 (All Versions), Modicon Premium Communication Modules: TSXETY4103, TSXETY5103 (All Versions) (high 7.5)
- [CVE-2021-22788](https://insights.sbomify.com/CVE-2021-22788/): Memory corruption in Modicon M340 CPUs: BMXP34 (Versions prior to V3.40), Modicon M340 X80 Ethernet Communication Modules: BMXNOE0100 (H), BMXNOE0110 (H), BMXNOC0401, BMXNOR0200H RTU (All Versions), Modicon Premium Processors with integrated Ethernet (Copro): TSXP574634, TSXP575634, TSXP576634 (All Versions), Modicon Quantum Processors with Integrated Ethernet (Copro): 140CPU65xxxxx (All Versions), Modicon Quantum Communication Modules: 140NOE771x1, 140NOC78x00, 140NOC77101 (All Versions), Modicon Premium Communication Modules: TSXETY4103, TSXETY5103 (All Versions) (high 7.5)
- [CVE-2020-7535](https://insights.sbomify.com/CVE-2020-7535/): Path traversal in Web Server on Modicon M340, Legacy Offers Modicon Quantum and Modicon Premium and associated Communication Modules (see security notification for affected versions) (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-7549 and fix it if it is affected.

What it is: CVE-2020-7549 is a high-severity denial of service vulnerability in Web Server on Modicon M340, Legacy Offers Modicon Quantum and Modicon Premium and associated Communication Modules (see security notification for affected versions), published on 11 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-2020-7549 in the wild and no public exploit code.

Affected product: Web Server on Modicon M340, Legacy Offers Modicon Quantum and Modicon Premium and associated Communication Modules (see security notification for affected versions). 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-2020-7549/ (Markdown: https://insights.sbomify.com/CVE-2020-7549/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-7549
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-7549
- OSV: https://osv.dev/vulnerability/CVE-2020-7549

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-7549/
Summaries are generated and may contain mistakes; the official description above is the record.