# CVE-2021-34561: Security feature bypass in WHA-GW-F2D2-0-AS- Z2-ETH

> Attackers can bypass IP or firewall access restrictions on the WirelessHART Gateway using DNS rebinding to proxy requests through the victim's browser.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/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:** A user has to click or open something
- **Fix available:** No
- **Published:** 31 Aug 2021
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-9fh3-r25p-cgrm

## What is CVE-2021-34561?

CVE-2021-34561 is a high-severity vulnerability in Phoenix Contact WHA-GW-F2D2-0-AS- Z2-ETH, published on 31 Aug 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

In PEPPERL+FUCHS WirelessHART-Gateway <= 3.0.8 serious issue exists, if the application is not externally accessible or uses IP-based access restrictions. Attackers can use DNS Rebinding to bypass any IP or firewall based access restrictions that may be in place, by proxying through their target's browser.

Weakness: CWE-350 (Reliance on Reverse DNS Resolution for a Security-Critical Action)

## Which versions are affected by CVE-2021-34561?

It affects 2 products.


Products: Pepperl-Fuchs Wha-Gw-F2d2-0-as-Z2-Eth.eip Firmware, Pepperl-Fuchs Wha-Gw-F2d2-0-as-Z2-Eth Firmware.

## How do I fix CVE-2021-34561?

No fix has been published for CVE-2021-34561 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-34561 being exploited?

There is no known exploitation of CVE-2021-34561 in the wild and no public exploit code.

## Other vulnerabilities in Phoenix Contact WHA-GW-F2D2-0-AS- Z2-ETH

- [CVE-2021-34565](https://insights.sbomify.com/CVE-2021-34565/): In WirelessHART-Gateway versions 3.0.7 to 3.0.9 hard-coded credentials have been found (critical 9.8)
- [CVE-2021-34560](https://insights.sbomify.com/CVE-2021-34560/): A vulnerability in WirelessHART-Gateway <= 3.0.9 could lead to information exposure of sensitive information (medium 5.5)
- [CVE-2021-34559](https://insights.sbomify.com/CVE-2021-34559/): Other in WHA-GW-F2D2-0-AS- Z2-ETH (medium 5.4)
- [CVE-2021-34562](https://insights.sbomify.com/CVE-2021-34562/): Cross-site scripting in WHA-GW-F2D2-0-AS- Z2-ETH (medium 5.4)
- [CVE-2021-34563](https://insights.sbomify.com/CVE-2021-34563/): Security feature bypass in WHA-GW-F2D2-0-AS- Z2-ETH (low 3.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-34561 and fix it if it is affected.

What it is: CVE-2021-34561 is a high-severity vulnerability in Phoenix Contact WHA-GW-F2D2-0-AS- Z2-ETH, published on 31 Aug 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-34561 in the wild and no public exploit code.

Affected product: Phoenix Contact WHA-GW-F2D2-0-AS- Z2-ETH. 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-2021-34561/ (Markdown: https://insights.sbomify.com/CVE-2021-34561/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-34561
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-34561
- OSV: https://osv.dev/vulnerability/CVE-2021-34561

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-34561/
Summaries are generated and may contain mistakes; the official description above is the record.