# CVE-2020-37216: Hirschmann HiOS denial of service in EtherNet/IP stack

Source: https://junglewise.ai/threats/cve-2020-37216-hirschmann-hios-denial-of-service-in-ethernet-ip-stack  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-03. Updated: 2026-07-25  
License: CC BY 4.0 with a link back

CVE-2020-37216 · Severity: high · CVSS 7.5 · Published 2026-04-03

Hirschmann HiOS is the operating system used in industrial network switches and routers. A security flaw in how these devices process industrial communication traffic allows a remote attacker to crash or freeze the device by sending a specially crafted network packet. This could lead to a complete loss of network connectivity and disruption of industrial operations until the hardware is manually reset or recovered.

Vendors: [Hirschmann](https://junglewise.ai/threats/vendors/hirschmann).

## Quick answers

**Is CVE-2020-37216 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2020-37216 being exploited in the wild.

**How severe is CVE-2020-37216?** High severity, with a CVSS score of 7.5, published 3 April 2026.

**Which products and versions are affected?** Hirschmann HiOS Prior to 08.1.00 and 07.1.01.

**Is there a fix for CVE-2020-37216?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2020-37216 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2020-37216?** Check whether you run Hirschmann HiOS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A denial of service vulnerability exists in the EtherNet/IP stack of Hirschmann HiOS due to improper input validation (CWE-20) of packet length fields. An unauthenticated remote attacker can exploit this by sending specially crafted UDP EtherNet/IP packets where the declared length value is larger than the actual packet size. This mismatch causes the device to crash or hang, rendering it inoperable. The vulnerability is resolved in HiOS versions 08.1.00, 07.1.01, and later.

## Affected products

- Hirschmann (Belden) HiOS Prior to 08.1.00 and 07.1.01

## Timeline

- 2026-04-03: advisory: Initial advisory published by VulnCheck and Belden

## References

- [https://assets.belden.com/m/3d3e2cbfa4860258/original/Belden-Security-Bulletin-BSECV-2019-14.pdf](https://assets.belden.com/m/3d3e2cbfa4860258/original/Belden-Security-Bulletin-BSECV-2019-14.pdf)
- [https://www.vulncheck.com/advisories/hirschmann-hios-ethernet-ip-stack-denial-of-service](https://www.vulncheck.com/advisories/hirschmann-hios-ethernet-ip-stack-denial-of-service)

## Related threats

- [Hirschmann HiOS Switch Platform denial of service in web interface](https://junglewise.ai/threats/cve-2025-15620-hirschmann-hios-switch-platform-denial-of-service-in-web)