CVE-2026-4436
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 · uneditedA low-privileged remote attacker can send Modbus packets to manipulate register values that are inputs to the odorant injection logic such that too much or too little odorant is injected into a gas line.
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 confidenceA vulnerability in gas odorization control systems allows a low-privileged remote attacker to manipulate Modbus register values that control odorant injection logic, causing excessive or insufficient odorant to be injected into natural gas lines. This affects safety-critical systems where odorant (typically mercaptan) enables leak detection.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- Changed
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
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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Identify gas odorization control systemsInventory your industrial control systems (ICS/SCADA) to locate any systems controlling odorant injection in natural gas distribution infrastructure. Check for PLCs, RTUs, or DCS systems specifically managing mercaptan or other odorant injection.Affected if You have deployed gas odorization control systems in your natural gas infrastructure.
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Verify Modbus exposureReview network segmentation and access controls for ICS networks. Check if Modbus (TCP/502 or serial) is accessible from less-trusted network zones or allows remote/IP-based connections.Affected if Modbus communication is exposed to network segments accessible by low-privileged or untrusted users.
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Check Modbus authenticationAudit Modbus device configurations and network policies to determine whether authentication, encryption, or allow-listing is required for write operations to holding registers.Affected if Modbus write commands to holding registers do not require authentication or authorization checks.
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Inspect odorant injection register accessReview Modbus register maps for your odorization controller. Identify holding registers (typically 40000-49999 range) controlling injection pump speed, valve positions, or injection timing. Check if these are writable without privilege elevation.Affected if Modbus registers controlling odorant injection parameters are writable by low-privileged or unauthenticated remote attackers.
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Review input validation on write commandsExamine the odorization controller logic or firmware to determine if range checking, rate limiting, or sanity validation is performed on incoming Modbus write requests before applying them to physical outputs.Affected if No input validation or range limits exist on Modbus write operations affecting odorant injection parameters.
You are affected if your gas odorization system uses Modbus-accessible controls for odorant injection without authentication, authorization, or input validation on register writes.
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 dataImplement Modbus authentication and input validation to reject unauthorized register writes; add rate limiting and anomaly detection on Modbus traffic; ensure physical interlocks or independent safety systems can override erroneous injection commands.
- Consultation8.0 h
- Implementation24.0 h
- Testing16.0 h
- Review / QA12.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $16,768.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-4436 — 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-2026-4436 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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- 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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