# CVE-2017-16726: Weak cryptography in Beckhoff TwinCAT

> Attackers can forge arbitrary ADS packets in Beckhoff TwinCAT due to lack of encryption, allowing unauthorized control or data manipulation in industrial environments.

- **Severity:** Critical 9.1 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 27 Jun 2018
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-3pcw-vp3f-6hvh

## What is CVE-2017-16726?

CVE-2017-16726 is a critical vulnerability in ICS-CERT Beckhoff TwinCAT, published on 27 Jun 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Beckhoff TwinCAT supports communication over ADS. ADS is a protocol for industrial automation in protected environments. ADS has not been designed to achieve security purposes and therefore does not include any encryption algorithms because of their negative effect on performance and throughput. An attacker can forge arbitrary ADS packets when legitimate ADS traffic is observable.

Weakness: CWE-326 (Inadequate Encryption Strength), CWE-285 (Improper Authorization)

## Which versions are affected by CVE-2017-16726?

It affects 1 product.


Products: Beckhoff Twincat.

## How do I fix CVE-2017-16726?

No fix has been published for CVE-2017-16726 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-16726 being exploited?

There is no known exploitation of CVE-2017-16726 in the wild and no public exploit code.

## Other vulnerabilities in ICS-CERT Beckhoff TwinCAT

- [CVE-2019-16871](https://insights.sbomify.com/CVE-2019-16871/): Auth bypass in n/a (critical 9.8)
- [CVE-2018-7502](https://insights.sbomify.com/CVE-2018-7502/): Privilege escalation in Beckhoff TwinCAT PLC products (high 7.8)
- [CVE-2019-5637](https://insights.sbomify.com/CVE-2019-5637/): Beckhoff TwinCAT Profinet Driver Divide-by-Zero Denial of Service (high 7.5)
- [CVE-2017-16718](https://insights.sbomify.com/CVE-2017-16718/): Weak cryptography in Beckhoff TwinCAT (medium 5.9)
- [CVE-2020-12494](https://insights.sbomify.com/CVE-2020-12494/): Beckhoff: Etherleak in TwinCAT RT network driver (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-16726 and fix it if it is affected.

What it is: CVE-2017-16726 is a critical vulnerability in ICS-CERT Beckhoff TwinCAT, published on 27 Jun 2018. 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-2017-16726 in the wild and no public exploit code.

Affected product: ICS-CERT Beckhoff TwinCAT. 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-2017-16726/ (Markdown: https://insights.sbomify.com/CVE-2017-16726/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-16726
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-16726
- OSV: https://osv.dev/vulnerability/CVE-2017-16726

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From sbomify Insights: https://insights.sbomify.com/CVE-2017-16726/
Summaries are generated and may contain mistakes; the official description above is the record.