Remote service crash via SendUnitData length underflow
Published Jul 13, 2026 · Updated Jul 13, 2026
Integer underflow in OpENer 2.3.0 allows remote attackers to crash the service via a crafted connected SendUnitData request. NotifyConnectedCommonPacketFormat subtracts two from an attacker-controlled data-item length of one without enforcing a minimum; the negative result converts to a large unsigned size and defeats the bounds check before DecodePaddedEPath reads beyond the stack receive buffer. Exploitation requires a registered EtherNet/IP session and valid CIP connection ID; the demonstrated consequence is immediate process termination, not proven code execution.
Summary
What happened
Integer underflow in OpENer 2.3.0 allows remote attackers to crash the service via a crafted connected SendUnitData request. NotifyConnectedCommonPacketFormat subtracts two from an attacker-controlled data-item length of one without enforcing a minimum; the negative result converts to a large unsigned size and defeats the bounds check before DecodePaddedEPath reads beyond the stack receive buffer. Exploitation requires a registered EtherNet/IP session and valid CIP connection ID; the demonstrated consequence is immediate process termination, not proven code execution.
The record
- CVE
- CVE-2026-51540
- Published
- Jul 13, 2026
- Updated
- Jul 13, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-191, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 13, 2026CVE publishedPublication date reported by the CVE source.
- Jul 13, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- SendUnitData integer-underflow proof of conceptfunctional · demonstrated
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Technologies
Your stack
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Your stack
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