# CVE-2021-34578: WAGO: Authentication Vulnerability in Web-Based Management

> Attackers can bypass authentication to read and modify settings on WAGO PLCs via the web-based management interface.

- **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:** 31 Aug 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-m68m-r5xj-h4vj

## What is CVE-2021-34578?

CVE-2021-34578 is a critical authentication bypass vulnerability in WAGO PLC, published on 31 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

This vulnerability allows an attacker who has access to the WBM to read and write settings-parameters of the device by sending specifically constructed requests without authentication on multiple WAGO PLCs in firmware versions up to FW07.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2021-34578?

It affects 12 products.


Products: Wago 750-362 Firmware, Wago 750-363 Firmware, Wago 750-823 Firmware, Wago 750-832\/000-002 Firmware, Wago 750-832 Firmware, Wago 750-862 Firmware, Wago 750-890\/025-000 Firmware, Wago 750-890\/025-001 Firmware, Wago 750-890\/025-002 Firmware, Wago 750-890\/040-000 Firmware, Wago 750-891 Firmware, Wago 750-893 Firmware.

## How do I fix CVE-2021-34578?

No fix has been published for CVE-2021-34578 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-34578 being exploited?

There is no known exploitation of CVE-2021-34578 in the wild and no public exploit code.

## Other vulnerabilities in WAGO PLC

- [CVE-2020-12506](https://insights.sbomify.com/CVE-2020-12506/): WAGO: Authentication Bypass Vulnerability in WAGO 750-36X and WAGO 750-8XX Versions <= FW03 (critical 9.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-34578 and fix it if it is affected.

What it is: CVE-2021-34578 is a critical authentication bypass vulnerability in WAGO PLC, published on 31 Aug 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-2021-34578 in the wild and no public exploit code.

Affected product: WAGO PLC. 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-2021-34578/ (Markdown: https://insights.sbomify.com/CVE-2021-34578/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-34578
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-34578
- OSV: https://osv.dev/vulnerability/CVE-2021-34578

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-34578/
Summaries are generated and may contain mistakes; the official description above is the record.