CVE-2026-54410
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 · uneditednanoMODBUS through v1.23.0 contains an off-by-one buffer overflow in the recv_msg_header function of the Modbus/TCP server that allows remote unauthenticated attackers to write one attacker-controlled byte past the end of the 260-byte receive buffer by sending a crafted MBAP frame whose Length field is set to 255.
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 · high confidenceAn off-by-one buffer overflow in nanoMODBUS library's recv_msg_header() function allows remote unauthenticated attackers to write one attacker-controlled byte past the end of a 260-byte receive buffer by sending a crafted Modbus/TCP MBAP frame with the Length field set to 255, corrupting an adjacent buffer-index field in the state structure and enabling denial of service through invalid memory accesses, and on bare-metal/RTOS targets without memory protection, limited information disclosure and writes to unintended register addresses via the Write Multiple Registers (FC16) handler.
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
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/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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Identify nanoMODBUS presenceSearch for nanoMODBUS library files or headers in the project (e.g., modbus.h, modbus.c, or any file referencing 'nanoMODBUS' in the codebase or installed packages)Affected if nanoMODBUS library is present and used for Modbus communication
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Determine installed versionCheck the version string in source files, headers, or build configuration (look for version macros or constants, often in modbus.h or similar header files)Affected if Version is v1.23.0 or earlier (the vulnerability affects through v1.23.0)
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Verify Modbus TCP (MBAP) processing is enabledInspect the code to confirm the application uses Modbus TCP transport (look for MBAP header parsing, typically involving recv_msg_header or similar function calls)Affected if The application processes Modbus TCP frames with MBAP headers using the vulnerable recv_msg_header function
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Check if Length field is validatedSearch the recv_msg_header function or its callers for bounds checking on the MBAP Length field; verify if Length > 253 (260-7) is rejected before buffer accessAffected if The MBAP Length field from network packets is not properly validated against buffer size before being used, allowing values up to 255 to trigger the overflow
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Monitor for crash or memory corruption indicatorsIf running, check logs/dmesg for crashes in recv_msg_header or adjacent memory corruption errors; look for unexpected behavior when processing Modbus TCP framesAffected if Application crashes or exhibits memory corruption when receiving Modbus TCP frames with Length field set to 255 (0xFF)
User is affected if nanoMODBUS v1.23.0 or earlier is in use and the application processes Modbus TCP frames with the vulnerable recv_msg_header function without proper Length field validation.
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 dataUpgrade to nanoMODBUS v1.23.1 or later which contains proper bounds checking in recv_msg_header(); if immediate patching is not possible, restrict network access to the Modbus/TCP service via firewall or network segmentation.
- Consultation4.0 h
- Implementation8.0 h
- Testing12.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-54410 — 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-2026-54410 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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