# CVE-2024-21785: Auth bypass in P3-550E

> Attackers can bypass authentication via leftover debug code in the Telnet interface to gain unauthorized access to the industrial controller.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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:** Not needed
- **Fix available:** No
- **Published:** 28 May 2024
- **Updated:** 13 Feb 2025

## What is CVE-2024-21785?

CVE-2024-21785 is a critical authentication bypass vulnerability in AutomationDirect P3-550E, published on 28 May 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A leftover debug code vulnerability exists in the Telnet Diagnostic Interface functionality of AutomationDirect P3-550E 1.2.10.9. A specially crafted series of network requests can lead to unauthorized access. An attacker can send a sequence of requests to trigger this vulnerability.

Weakness: CWE-489 (Active Debug Code)

## Which versions are affected by CVE-2024-21785?

It affects 6 products.


Products: Automationdirect P1-540 Firmware, Automationdirect P1-550 Firmware, Automationdirect P2-550 Firmware, Automationdirect P3-530 Firmware, Automationdirect P3-550 Firmware, Automationdirect P3-550e Firmware.

## How do I fix CVE-2024-21785?

No fix has been published for CVE-2024-21785 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-21785 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2024-21785 exists.

## Other vulnerabilities in AutomationDirect P3-550E

- [CVE-2024-23601](https://insights.sbomify.com/CVE-2024-23601/): Code injection in P3-550E (critical 9.8)
- [CVE-2024-24962](https://insights.sbomify.com/CVE-2024-24962/): Memory corruption in P3-550E (critical 9.8)
- [CVE-2024-24963](https://insights.sbomify.com/CVE-2024-24963/): Memory corruption in P3-550E (critical 9.8)
- [CVE-2024-22187](https://insights.sbomify.com/CVE-2024-22187/): Memory corruption in P3-550E (critical 9.1)
- [CVE-2024-24946](https://insights.sbomify.com/CVE-2024-24946/): Memory corruption in P3-550E (high 8.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-21785 and fix it if it is affected.

What it is: CVE-2024-21785 is a critical authentication bypass vulnerability in AutomationDirect P3-550E, published on 28 May 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2024-21785 exists.

Affected product: AutomationDirect P3-550E. 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-2024-21785/ (Markdown: https://insights.sbomify.com/CVE-2024-21785/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-21785
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-21785
- OSV: https://osv.dev/vulnerability/CVE-2024-21785

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-21785/
Summaries are generated and may contain mistakes; the official description above is the record.