# CVE-2017-7937: Auth bypass in Phoenix Contact GmbH mGuard

> Attackers can bypass authentication on Phoenix Contact mGuard firewalls when RADIUS servers are unreachable, gaining unauthorized access.

- **Severity:** Medium 4.0 (`CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 19 May 2017
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-93xj-xqmv-6cxx

## What is CVE-2017-7937?

CVE-2017-7937 is a medium-severity authentication bypass vulnerability in Phoenix Contact GmbH mGuard, published on 19 May 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An Improper Authentication issue was discovered in Phoenix Contact GmbH mGuard firmware versions 8.3.0 to 8.4.2. An attacker may be able to gain unauthorized access to the user firewall when RADIUS servers are unreachable.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2017-7937?

It affects 1 product.


Products: Phoenix Contact Gmbh Mguard Firmware.

## How do I fix CVE-2017-7937?

No fix has been published for CVE-2017-7937 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-7937 being exploited?

There is no known exploitation of CVE-2017-7937 in the wild and no public exploit code.

## Other vulnerabilities in Phoenix Contact GmbH mGuard

- [CVE-2017-7935](https://insights.sbomify.com/CVE-2017-7935/): Denial of service in Phoenix Contact GmbH mGuard (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-7937 and fix it if it is affected.

What it is: CVE-2017-7937 is a medium-severity authentication bypass vulnerability in Phoenix Contact GmbH mGuard, published on 19 May 2017. 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-2017-7937 in the wild and no public exploit code.

Affected product: Phoenix Contact GmbH mGuard. 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-2017-7937/ (Markdown: https://insights.sbomify.com/CVE-2017-7937/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-7937
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-7937
- OSV: https://osv.dev/vulnerability/CVE-2017-7937

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-7937/
Summaries are generated and may contain mistakes; the official description above is the record.