# CVE-2020-7533: Auth bypass in Web Server on Modicon M340, Modicon Quantum and Modicon Premium Legacy offers and their Communication Modules (see security notification for version information)

> Unauthenticated attackers can execute commands on Modicon PLC web servers via crafted HTTP requests, requiring immediate patching for industrial control systems.

- **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:** 1 Dec 2020
- **Updated:** 10 Jun 2025
- **Also known as:** GHSA-4wm4-5vmp-66g7

## What is CVE-2020-7533?

CVE-2020-7533 is a critical authentication bypass vulnerability in Web Server on Modicon M340, Modicon Quantum and Modicon Premium Legacy offers and their Communication Modules (see security notification for version information), published on 1 Dec 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

CWE-287: Improper Authentication vulnerability exists which could cause the execution of
commands on the webserver without authentication when sending specially crafted HTTP
requests.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2020-7533?

It affects 16 products.


Products: Schneider-Electric 140cpu65260 Firmware, Schneider-Electric 140noc77101 Firmware, Schneider-Electric 140noc78000 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 Bmxp3420302 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-2020-7533?

No fix has been published for CVE-2020-7533 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-7533 being exploited?

There is no known exploitation of CVE-2020-7533 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-7533 and fix it if it is affected.

What it is: CVE-2020-7533 is a critical authentication bypass vulnerability in Web Server on Modicon M340, Modicon Quantum and Modicon Premium Legacy offers and their Communication Modules (see security notification for version information), published on 1 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-2020-7533 in the wild and no public exploit code.

Affected product: Web Server on Modicon M340, Modicon Quantum and Modicon Premium Legacy offers and their Communication Modules (see security notification for version information). 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-2020-7533/ (Markdown: https://insights.sbomify.com/CVE-2020-7533/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-7533
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-7533
- OSV: https://osv.dev/vulnerability/CVE-2020-7533

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-7533/
Summaries are generated and may contain mistakes; the official description above is the record.