# CVE-2020-12523: Security feature bypass in FL MGUARD RS4004 TX/DTX (2701876)

> Disabled LAN ports on Phoenix Contact mGuard devices become active after reboot, bypassing security configurations and exposing network segments.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L`)
- **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:** 17 Dec 2020
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-fwfg-74jc-wgx8

## What is CVE-2020-12523?

CVE-2020-12523 is a medium-severity vulnerability in Innominate FL MGUARD RS4004 TX/DTX (2701876), published on 17 Dec 2020. 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

On Phoenix Contact mGuard Devices versions before 8.8.3 LAN ports get functional after reboot even if they are disabled in the device configuration. For mGuard devices with integrated switch on the LAN side, single switch ports can be disabled by device configuration. After a reboot these ports get functional independent from their configuration setting: Missing Initialization of Resource

Weakness: CWE-909 (Missing Initialization of Resource)

## Which versions are affected by CVE-2020-12523?

It affects 9 products.


Products: Phoenixcontact Fl Mguard Rs4004 Tx\/Dtx Firmware, Phoenixcontact Fl Mguard Rs4004 Tx\/Dtx Vpn Firmware, Phoenixcontact Innominate Mguard Rs4000 4tx\/3g\/Tx Vpn Firmware, Phoenixcontact Innominate Mguard Rs4000 4tx\/Tx Firmware, Phoenixcontact Innominate Mguard Rs4000 4tx\/Tx Vpn Firmware, Phoenixcontact Tc Mguard Rs4000 3g Vpn Firmware, Phoenixcontact Tc Mguard Rs4000 4g Att Vpn Firmware, Phoenixcontact Tc Mguard Rs4000 4g Vpn Firmware, Phoenixcontact Tc Mguard Rs4000 4g Vzw Vpn Firmware.

## How do I fix CVE-2020-12523?

No fix has been published for CVE-2020-12523 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-12523 being exploited?

There is no known exploitation of CVE-2020-12523 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-12523 and fix it if it is affected.

What it is: CVE-2020-12523 is a medium-severity vulnerability in Innominate FL MGUARD RS4004 TX/DTX (2701876), published on 17 Dec 2020. 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-2020-12523 in the wild and no public exploit code.

Affected product: Innominate FL MGUARD RS4004 TX/DTX (2701876). 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-2020-12523/ (Markdown: https://insights.sbomify.com/CVE-2020-12523/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-12523
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-12523
- OSV: https://osv.dev/vulnerability/CVE-2020-12523

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-12523/
Summaries are generated and may contain mistakes; the official description above is the record.