# CVE-2021-34581: WAGO: Denial of Service vulnerability inside the OpenSSL implementation

> An unauthenticated attacker can cause a denial of service on WAGO I/O controllers due to a resource management flaw in the OpenSSL implementation.

- **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:** 31 Aug 2021
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-v448-m2g5-fm7c

## What is CVE-2021-34581?

CVE-2021-34581 is a high-severity denial of service vulnerability in WAGO 750-831/xxx-xxx, 750-880/xxx-xxx, 750-881, 750-889, published on 31 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Missing Release of Resource after Effective Lifetime vulnerability in OpenSSL implementation of WAGO 750-831/xxx-xxx, 750-880/xxx-xxx, 750-881, 750-889 in versions FW4 up to FW15 allows an unauthenticated attacker to cause DoS on the device.

Weakness: CWE-772 (Missing Release of Resource after Effective Lifetime)

## Which versions are affected by CVE-2021-34581?

It affects 9 products.


Products: Wago 750-831\/000-002 Firmware, Wago 750-831 Firmware, Wago 750-880\/025-000 Firmware, Wago 750-880\/025-001 Firmware, Wago 750-880\/025-002 Firmware, Wago 750-880\/040-000 Firmware, Wago 750-880 Firmware, Wago 750-881 Firmware, Wago 750-889 Firmware.

## How do I fix CVE-2021-34581?

No fix has been published for CVE-2021-34581 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-34581 being exploited?

There is no known exploitation of CVE-2021-34581 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-34581 and fix it if it is affected.

What it is: CVE-2021-34581 is a high-severity denial of service vulnerability in WAGO 750-831/xxx-xxx, 750-880/xxx-xxx, 750-881, 750-889, 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-2021-34581 in the wild and no public exploit code.

Affected product: WAGO 750-831/xxx-xxx, 750-880/xxx-xxx, 750-881, 750-889. 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-2021-34581/ (Markdown: https://insights.sbomify.com/CVE-2021-34581/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-34581
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-34581
- OSV: https://osv.dev/vulnerability/CVE-2021-34581

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-34581/
Summaries are generated and may contain mistakes; the official description above is the record.