CVE-2026-51540
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 · uneditedOpENer 2.3.0 (master branch up to commit 76b95cf) is vulnerable to a severe memory corruption issue caused by an integer underflow in the processing of connected explicit messages (SendUnitData).
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 confidenceOpENer 2.3.0 contains an integer underflow vulnerability in the processing of connected explicit messages via the SendUnitData function. This allows memory corruption when handling malformed network packets with insufficient size validation, potentially enabling remote code execution.
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= 2.3.0CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 checksWork through these to decide whether this CVE applies to you.
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Confirm OpENer installationIdentify if OpENer software is present on the system by searching for the binary, service, or running process (commonly named 'opener' or 'OpENer'). Check installed packages or running services on industrial devices.Affected if OpENer software is found running or installed on the system
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Determine installed versionQuery the OpENer version using --version flag, checking binary metadata, or examining the source code repository if accessible. Compare the version against 2.3.0.Affected if The installed version is exactly 2.3.0 or falls within the affected version range based on available version information
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Verify network exposure of SendUnitData functionDetermine if the OpENer service is listening on network ports (typical EtherNet/IP ports 44818, 2222). Check firewall rules and network configuration to assess if the service accepts remote connections.Affected if The OpENer service is network-accessible and processing EtherNet/IP connected explicit messages from untrusted sources
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Inspect packet handling configurationReview OpENer configuration files and logs for accepted connections and message types. Check if connected explicit message processing is enabled in the EtherNet/IP stack.Affected if Connected explicit message processing is enabled and the service handles CIP traffic from network sources
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Check for vulnerable code path in sourceIf source code is accessible, search for the SendUnitData function and verify if length validation on message buffers includes proper integer overflow/underflow checks before memory allocation.Affected if The SendUnitData function lacks proper size validation and integer underflow guards on message length fields
The system is affected if OpENer version 2.3.0 is running and processing network traffic, as the integer underflow vulnerability in SendUnitData triggers during malformed packet handling.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor dataUpdate OpENer beyond commit 76b95cf or implement proper integer overflow checks and bounds validation on message length fields before memory allocation operations in SendUnitData processing.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,888.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-51540 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-51540 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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
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