# CVE-2021-22731: Auth bypass in Modicon Managed Switch MCSESM* and MCSESP* V8.21 and prior

> Remote attackers can change passwords via HTTP/HTTPS if basic user info is known, leading to unauthorized access on Modicon switches.

- **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:** 26 May 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-6q5v-82v5-mpf9

## What is CVE-2021-22731?

CVE-2021-22731 is a critical authentication bypass vulnerability in Modicon Managed Switch MCSESM* and MCSESP* V8.21 and prior, published on 26 May 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Weak Password Recovery Mechanism for Forgotten Password vulnerability exists on Modicon Managed Switch MCSESM* and MCSESP* V8.21 and prior which could cause an unauthorized password change through HTTP / HTTPS when basic user information is known by a remote attacker.

Weakness: CWE-640 (Weak Password Recovery Mechanism for Forgotten Password)

## Which versions are affected by CVE-2021-22731?

It affects 16 products.


Products: Schneider-Electric Mcsesm043f23f0 Firmware, Schneider-Electric Mcsesm053f1cs0 Firmware, Schneider-Electric Mcsesm053f1cu0 Firmware, Schneider-Electric Mcsesm063f2cs0 Firmware, Schneider-Electric Mcsesm063f2cu0 Firmware, Schneider-Electric Mcsesm083f23f0 Firmware, Schneider-Electric Mcsesm083f23f0h Firmware, Schneider-Electric Mcsesm093f1cs0 Firmware, Schneider-Electric Mcsesm093f1cu0 Firmware, Schneider-Electric Mcsesm103f2cs0 Firmware, Schneider-Electric Mcsesm103f2cs0h Firmware, Schneider-Electric Mcsesm103f2cu0 Firmware, Schneider-Electric Mcsesm103f2cu0h Firmware, Schneider-Electric Mcsesm123f2lg0 Firmware, Schneider-Electric Mcsesp083f23g0 Firmware, Schneider-Electric Mcsesp083f23g0t Firmware.

## How do I fix CVE-2021-22731?

No fix has been published for CVE-2021-22731 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-22731 being exploited?

There is no known exploitation of CVE-2021-22731 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-22731 and fix it if it is affected.

What it is: CVE-2021-22731 is a critical authentication bypass vulnerability in Modicon Managed Switch MCSESM* and MCSESP* V8.21 and prior, published on 26 May 2021. 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-2021-22731 in the wild and no public exploit code.

Affected product: Modicon Managed Switch MCSESM* and MCSESP* V8.21 and prior. 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-2021-22731/ (Markdown: https://insights.sbomify.com/CVE-2021-22731/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-22731
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-22731
- OSV: https://osv.dev/vulnerability/CVE-2021-22731

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-22731/
Summaries are generated and may contain mistakes; the official description above is the record.