# CVE-2020-12521: Denial of service in AXC F 1152 (1151412)

> A specially crafted LLDP packet can cause high system load, leading to service failure or reboot on Phoenix Contact PLCnext Control Devices.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:A/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:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 17 Dec 2020
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-vp46-jgwp-q8w3

## What is CVE-2020-12521?

CVE-2020-12521 is a medium-severity denial of service vulnerability in Phoenix Contact AXC F 1152 (1151412), published on 17 Dec 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

On Phoenix Contact PLCnext Control Devices versions before 2021.0 LTS a specially crafted LLDP packet may lead to a high system load in the PROFINET stack. An attacker can cause failure of system services or a complete reboot.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2020-12521?

It affects 1 product.


Products: Phoenixcontact Plcnext Firmware.

## How do I fix CVE-2020-12521?

No fix has been published for CVE-2020-12521 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-12521 being exploited?

There is no known exploitation of CVE-2020-12521 in the wild and no public exploit code.

## Other vulnerabilities in Phoenix Contact AXC F 1152 (1151412)

- [CVE-2020-12517](https://insights.sbomify.com/CVE-2020-12517/): Cross-site scripting in AXC F 1152 (1151412) (high 8.8)
- [CVE-2020-12519](https://insights.sbomify.com/CVE-2020-12519/): Privilege escalation in AXC F 1152 (1151412) (high 8.8)
- [CVE-2020-12518](https://insights.sbomify.com/CVE-2020-12518/): Information disclosure in AXC F 1152 (1151412) (medium 5.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-12521 and fix it if it is affected.

What it is: CVE-2020-12521 is a medium-severity denial of service vulnerability in Phoenix Contact AXC F 1152 (1151412), published on 17 Dec 2020. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-12521 in the wild and no public exploit code.

Affected product: Phoenix Contact AXC F 1152 (1151412). 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-2020-12521/ (Markdown: https://insights.sbomify.com/CVE-2020-12521/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-12521
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-12521
- OSV: https://osv.dev/vulnerability/CVE-2020-12521

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-12521/
Summaries are generated and may contain mistakes; the official description above is the record.