CVE-2020-37216Network attack vector

Device crash via oversized EtherNet/IP length field

Published Apr 3, 2026 · Updated Apr 3, 2026

Improper input validation in Belden Hirschmann HiOS 05.0.00 through 08.0.00 allows remote attackers to crash or hang switch devices. The EtherNet/IP stack trusts a UDP header length larger than the received packet and enters a state that crashes or stalls protocol processing. Exploitation requires EtherNet/IP to be enabled and network access to its UDP port; the switch can become inoperable.

CVSS severity8.7
High
EPSS probability0.92%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Belden Hirschmann HiOS 05.0.00 through 08.0.00 allows remote attackers to crash or hang switch devices. The EtherNet/IP stack trusts a UDP header length larger than the received packet and enters a state that crashes or stalls protocol processing. Exploitation requires EtherNet/IP to be enabled and network access to its UDP port; the switch can become inoperable.

The record

CVE
CVE-2020-37216
Published
Apr 3, 2026
Updated
Apr 3, 2026
Vendor
Belden
Product
Hirschmann HiOS
Classifications
CWE-20, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=05.00.00 <=08.0.00

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Belden · Hirschmann HiOSversion=05.00.00 <=08.0.00

Published CVSS scores

8.7VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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