# CVE-2021-33540: Phoenix Contact: Undocumented FTP acces in certain AXL F BK and IL BK devices

> Undocumented FTP access with a password allows attackers to read and modify files on Phoenix Contact industrial network bridges.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 25 Jun 2021
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-vgp3-9m7m-h7cr

## What is CVE-2021-33540?

CVE-2021-33540 is a high-severity vulnerability in Phoenix Contact AXL F BK, published on 25 Jun 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In certain devices of the Phoenix Contact AXL F BK and IL BK product families an undocumented password protected FTP access to the root directory exists.

Weakness: CWE-798 (Use of Hard-coded Credentials)

## Which versions are affected by CVE-2021-33540?

It affects 18 products.


Products: Phoenixcontact Axl F Bk Eip Ef Firmware, Phoenixcontact Axl F Bk Eip Firmware, Phoenixcontact Axl F Bk Eth Firmware, Phoenixcontact Axl F Bk Eth Net2 Firmware, Phoenixcontact Axl F Bk Eth Xc Firmware, Phoenixcontact Axl F Bk Pn Firmware, Phoenixcontact Axl F Bk Pn Tps Firmware, Phoenixcontact Axl F Bk Pn Tps Xc Firmware, Phoenixcontact Axl F Bk Pn Xc Firmware, Phoenixcontact Axl F Bk S35 Firmware, Phoenixcontact Axl F Bk Sas Firmware, Phoenixcontact Il Eip Bk Di8 Do4 2tx-Pac Firmware, Phoenixcontact Il Eth Bk Di8 Do4 2tx-Pac Firmware, Phoenixcontact Il Eth Bk Di8 Do4 2tx-Xc-Pac Firmware, Phoenixcontact Il Pn Bk-Pac Firmware, Phoenixcontact Il Pn Bk Di8 Do4 2scrj-Pac Firmware, Phoenixcontact Il Pn Bk Di8 Do4 2tx-Pac Firmware, Phoenixcontact Il S3 Bk Di8 Do4 2tx-Pac Firmware.

## How do I fix CVE-2021-33540?

No fix has been published for CVE-2021-33540 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-33540 being exploited?

There is no known exploitation of CVE-2021-33540 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-33540 and fix it if it is affected.

What it is: CVE-2021-33540 is a high-severity vulnerability in Phoenix Contact AXL F BK, published on 25 Jun 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-2021-33540 in the wild and no public exploit code.

Affected product: Phoenix Contact AXL F BK. 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-2021-33540/ (Markdown: https://insights.sbomify.com/CVE-2021-33540/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-33540
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-33540
- OSV: https://osv.dev/vulnerability/CVE-2021-33540

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-33540/
Summaries are generated and may contain mistakes; the official description above is the record.