# CVE-2021-22786: Information disclosure in Legacy Modicon Quantum

> Attackers can expose sensitive memory information from Modicon PLCs via Modbus TCP, requiring firmware upgrades for mitigation.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 Feb 2023
- **Updated:** 5 Feb 2025
- **Also known as:** GHSA-c8j6-69w9-74h6

## What is CVE-2021-22786?

CVE-2021-22786 is a high-severity vulnerability in Schneider Electric Legacy Modicon Quantum, published on 1 Feb 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A CWE-200: Information Exposure vulnerability exists that could cause the exposure of sensitive information stored on the memory of the controller when communicating over the Modbus TCP protocol. Affected Products: Modicon M340 CPU (part numbers BMXP34*) (Versions prior to V3.30), Modicon M580 CPU (part numbers BMEP* and BMEH*) (Versions prior to SV3.20), Modicon MC80 (BMKC80) (Versions prior to V1.6), Modicon M580 CPU Safety (part numbers BMEP58*S and BMEH58*S) (All Versions), Modicon Momentum MDI (171CBU*) (Versions prior to V2.3), Legacy Modicon Quantum (All Versions)

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2021-22786?

It affects 41 products.


Products: Schneider-Electric Modicon M340 Bmxp341000 Firmware, Schneider-Electric Modicon M340 Bmxp342000 Firmware, Schneider-Electric Modicon M340 Bmxp3420102 Firmware, Schneider-Electric Modicon M340 Bmxp342010 Firmware, Schneider-Electric Modicon M340 Bmxp342020 Firmware, Schneider-Electric Modicon M340 Bmxp342020h Firmware, Schneider-Electric Modicon M340 Bmxp3420302 Firmware, Schneider-Electric Modicon M340 Bmxp3420302h Firmware, Schneider-Electric Modicon M340 Bmxp342030 Firmware, Schneider-Electric Modicon M340 Bmxp342030h Firmware, Schneider-Electric Modicon M580 Bmeh582040 Firmware, Schneider-Electric Modicon M580 Bmeh582040c Firmware, Schneider-Electric Modicon M580 Bmeh582040s Firmware, Schneider-Electric Modicon M580 Bmeh584040 Firmware, Schneider-Electric Modicon M580 Bmeh584040c Firmware, Schneider-Electric Modicon M580 Bmeh584040s Firmware, Schneider-Electric Modicon M580 Bmeh586040 Firmware, Schneider-Electric Modicon M580 Bmeh586040c Firmware, Schneider-Electric Modicon M580 Bmeh586040s Firmware, Schneider-Electric Modicon M580 Bmep581020 Firmware and 21 more.

## How do I fix CVE-2021-22786?

No fix has been published for CVE-2021-22786 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-22786 being exploited?

There is no known exploitation of CVE-2021-22786 in the wild and no public exploit code.

## Other vulnerabilities in Schneider Electric Legacy Modicon Quantum

- [CVE-2022-22724](https://insights.sbomify.com/CVE-2022-22724/): Denial of service in Modicon M340 CPUs: BMXP34 (All Versions) (high 7.5)
- [CVE-2020-7537](https://insights.sbomify.com/CVE-2020-7537/): Denial of service in Modicon M580, Modicon M340, Legacy Controllers Modicon Quantum & Modicon Premium (see security notifications for affected versions) (high 7.5)
- [CVE-2020-7543](https://insights.sbomify.com/CVE-2020-7543/): Denial of service in Modicon M580, Modicon M340, Legacy Controllers Modicon Quantum & Modicon Premium (see security notifications for affected versions) (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-22786 and fix it if it is affected.

What it is: CVE-2021-22786 is a high-severity vulnerability in Schneider Electric Legacy Modicon Quantum, published on 1 Feb 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-2021-22786 in the wild and no public exploit code.

Affected product: Schneider Electric Legacy Modicon Quantum. 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-2021-22786/ (Markdown: https://insights.sbomify.com/CVE-2021-22786/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-22786
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-22786
- OSV: https://osv.dev/vulnerability/CVE-2021-22786

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-22786/
Summaries are generated and may contain mistakes; the official description above is the record.