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OpenerApplication · Opener Project

CVE-2021-27478

HIGH · 7.5 CVSS v3.1 Published 2022-05-12
Fix available
A fix is available. Upgrade to after 2.3 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A specifically crafted packet sent by an attacker to EIPStackGroup OpENer EtherNet/IP commits and versions prior to Feb 10, 2021 may cause a denial-of-service condition.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A specifically crafted packet sent to EIPStackGroup OpENer EtherNet/IP (versions prior to Feb 10, 2021) can trigger a denial-of-service condition. The vulnerability is network-exploitable with no authentication required, indicating a vulnerability in packet handling logic within the EtherNet/IP server component.

MitigationUpdate to the patched version of OpENer released on or after February 10, 2021. If immediate patching is not possible, consider network segmentation to limit exposure of the affected EtherNet/IP service to untrusted networks.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
OpenerApplication
Affected:<= 2.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify OpENer installation
    Search for OpENer or EIPStackGroup software components in your environment, including running processes, installed applications, or embedded device firmware that may contain the EtherNet/IP server.
    Affected if OpENer EtherNet/IP software is present in the environment
  2. Determine installed version
    Locate the version information for the OpENer installation (check application metadata, binary version info, or documentation). Compare this version against the affected range: versions prior to the Feb 10, 2021 update.
    Affected if The installed version is 2.3 or earlier, or any version released before February 10, 2021
  3. Verify EtherNet/IP server is active
    Confirm that the EtherNet/IP server component is enabled and running. This vulnerability affects packet handling logic specifically within the EtherNet/IP server, so an inactive server would not be exploitable.
    Affected if The EtherNet/IP server component is running or enabled
  4. Assess network exposure
    Determine if the EtherNet/IP service is exposed to network access from untrusted sources. Check firewall rules, network segmentation, and direct IP accessibility of the service port.
    Affected if The EtherNet/IP service is accessible from untrusted networks without network segmentation protections

Your environment is affected if OpENer version 2.3 or earlier is installed with the EtherNet/IP server component running and exposed to network access.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 2.3
Interim mitigation

Update to the patched version of OpENer released on or after February 10, 2021. If immediate patching is not possible, consider network segmentation to limit exposure of the affected EtherNet/IP service to untrusted networks.

Recommended fix Moderate confidence

Upgrade to OpENer version 2.3.1 or later (any version released after February 10, 2021)

  1. 1. Identify the current version of OpENer (Opener) being used in your environment
  2. 2. Navigate to the official OpENer GitHub repository (github.com/EIPStackGroup/OpENer)
  3. 3. Check the releases or commits section for versions released after February 10, 2021
  4. 4. Download or reference the latest stable release (version 2.3.1 or later if available)
  5. 5. Review the release notes or changelog to confirm the vulnerability fix is included
  6. 6. Test the new version in a staging environment before production deployment
  7. 7. Deploy the upgraded version to production systems
Caveat Review release notes for any API or compatibility changes between versions; test thoroughly before production deployment

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Opener Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-27478 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data