CVE-2026-51538Public exploitNetwork attack vector

Unauthenticated session hijacking via unbound handles

Published Jul 13, 2026 · Updated Jul 13, 2026

Improper access control in EIPStackGroup OpENer 2.3.0 allows remote attackers to hijack or terminate EtherNet/IP sessions. CheckRegisteredSessions in source/src/enet_encap/encap.c validates only that a session_handle is active, not that the issuing TCP socket owns it. A handle from another active client is required; predictable handles permit unauthenticated command processing and interruption of legitimate industrial communications.

CVSS severity9.1
Critical
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in EIPStackGroup OpENer 2.3.0 allows remote attackers to hijack or terminate EtherNet/IP sessions. CheckRegisteredSessions in source/src/enet_encap/encap.c validates only that a session_handle is active, not that the issuing TCP socket owns it. A handle from another active client is required; predictable handles permit unauthenticated command processing and interruption of legitimate industrial communications.

The record

CVE
CVE-2026-51538
Published
Jul 13, 2026
Updated
Jul 13, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-284
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 13, 2026CVE publishedPublication date reported by the CVE source.
  2. 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-284Improper Access Control

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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