# CVE-2020-12494: Beckhoff: Etherleak in TwinCAT RT network driver

> An attacker can read arbitrary memory contents from the network driver by sending small ICMP packets, potentially exposing sensitive data.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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:** 16 Jun 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-92f3-r9r6-rrfr

## What is CVE-2020-12494?

CVE-2020-12494 is a medium-severity vulnerability in Beckhoff TwinCat Driver for Intel 8254x (Tcl8254x.sys), published on 16 Jun 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Beckhoff's TwinCAT RT network driver for Intel 8254x and 8255x is providing EtherCAT functionality. The driver implements real-time features. Except for Ethernet frames sent from real-time functionality, all other Ethernet frames sent through the driver are not padded if their payload is less than the minimum Ethernet frame size. Instead, arbitrary memory content is transmitted within in the padding bytes of the frame. Most likely this memory contains slices from previously transmitted or received frames. By this method, memory content is disclosed, however, an attacker can hardly control which memory content is affected. For example, the disclosure can be provoked with small sized ICMP echo requests sent to the device.

Weakness: CWE-459 (Incomplete Cleanup)

## Which versions are affected by CVE-2020-12494?

It affects 2 products.


Products: Beckhoff Twincat, Beckhoff Twincat Driver.

## How do I fix CVE-2020-12494?

No fix has been published for CVE-2020-12494 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-12494 being exploited?

There is no known exploitation of CVE-2020-12494 in the wild and no public exploit code.

## Other vulnerabilities in Beckhoff TwinCat Driver for Intel 8254x (Tcl8254x.sys)

- [CVE-2019-16871](https://insights.sbomify.com/CVE-2019-16871/): Auth bypass in n/a (critical 9.8)
- [CVE-2017-16726](https://insights.sbomify.com/CVE-2017-16726/): Weak cryptography in Beckhoff TwinCAT (critical 9.1)
- [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)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-12494 and fix it if it is affected.

What it is: CVE-2020-12494 is a medium-severity vulnerability in Beckhoff TwinCat Driver for Intel 8254x (Tcl8254x.sys), published on 16 Jun 2020. 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-2020-12494 in the wild and no public exploit code.

Affected product: Beckhoff TwinCat Driver for Intel 8254x (Tcl8254x.sys). 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-2020-12494/ (Markdown: https://insights.sbomify.com/CVE-2020-12494/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-12494
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-12494
- OSV: https://osv.dev/vulnerability/CVE-2020-12494

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-12494/
Summaries are generated and may contain mistakes; the official description above is the record.