CVE-2021-27498Network attack vector

Unauthenticated service crash via invalid CIP path

Published May 12, 2022 · Updated Apr 16, 2025

Reachable assertion in OpENer before February 10, 2021 allows remote attackers to crash the EtherNet/IP service with a crafted packet. GetPathSegmentType treats an invalid CIP path segment as an impossible state and calls OPENER_ASSERT(false) instead of returning an error. No authentication or user interaction is required; network access to the EtherNet/IP listener is sufficient to terminate the process and interrupt adapter communications.

CVSS severity7.5
High
EPSS probability1.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in OpENer before February 10, 2021 allows remote attackers to crash the EtherNet/IP service with a crafted packet. GetPathSegmentType treats an invalid CIP path segment as an impossible state and calls OPENER_ASSERT(false) instead of returning an error. No authentication or user interaction is required; network access to the EtherNet/IP listener is sufficient to terminate the process and interrupt adapter communications.

The record

CVE
CVE-2021-27498
Published
May 12, 2022
Updated
Apr 16, 2025
Vendor
EIPStackGroup
Product
OpENer
Classifications
CWE-617, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 12, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 16, 2025Record 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=unspecified <Feb 10, 2021

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

EIPStackGroup · OpENerversion=unspecified <Feb 10, 2021

Published CVSS scores

5.0NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5CISA ICS-CERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NVDCVSS: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-617Reachable Assertion
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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