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Vulnerability record · CVE-2026-51538 · published 13 July 2026

CVE-2026-51538: Opener project opener improper access control vulnerability

Opener Project · Opener

EIPStackGroup OpENer 2.3.0 (commit 76b95cf) suffers from an Incorrect Access Control vulnerability in its handling of encapsulation sessions. When the server processes critical encapsulation commands, it verifies whether the provided session_handle exists in the global session list, but it fails to verify whether that handle belongs to the specific TCP connection issuing the request. Because there is no strong binding between a session handle and its originating socket, any attacker on the network can use a valid session handle created by another legitimate client to bypass access controls.

9.1 CVSS 3.1 Critical EPSS 0.52% · top 58.0% CWE-284 · Improper access control
9.1CVSS 3.1 base score
0.52%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References, 2 tagged exploit
11 Aug 2026Last modified by NVD

Description

EIPStackGroup OpENer 2.3.0 (commit 76b95cf) suffers from an Incorrect Access Control vulnerability in its handling of encapsulation sessions. When the server processes critical encapsulation commands, it verifies whether the provided session_handle exists in the global session list, but it fails to verify whether that handle belongs to the specific TCP connection issuing the request. Because there is no strong binding between a session handle and its originating socket, any attacker on the network can use a valid session handle created by another legitimate client to bypass access controls.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://gist.github.com/MrAlaskan/8156ca3acd6754a9f66efede0a1351f2 Third Party Advisory
https://github.com/EIPStackGroup/OpENer/issues/565 ExploitIssue TrackingVendor Advisory
https://github.com/EIPStackGroup/OpENer/issues/565 ExploitIssue TrackingVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

10.0CVE-2021-21777Opener project opener out-of-bounds read vulnerabilityAn information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer 2.3 and development commit 8c73…EPSS 1.7%9.8CVE-2026-51540Opener project opener vulnerabilityOpENer 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 …EPSS 0.57%9.8CVE-2022-43604Opener project opener out-of-bounds write vulnerabilityAn out-of-bounds write vulnerability exists in the GetAttributeList attribute_count_request functionality of EIP Stack Group OpENer development commi…EPSS 14%9.8CVE-2022-43605Opener project opener out-of-bounds write vulnerabilityAn out-of-bounds write vulnerability exists in the SetAttributeList attribute_count_request functionality of EIP Stack Group OpENer development commi…EPSS 14%9.8CVE-2020-13556Opener project opener out-of-bounds write vulnerabilityAn out-of-bounds write vulnerability exists in the Ethernet/IP server functionality of EIP Stack Group OpENer 2.3 and development commit 8c73bf3. A s…EPSS 4.7%9.1CVE-2026-51536Opener project opener integer overflow vulnerabilityIn OpENer 2.3.0 (commit 76b95cf) when parsing incoming CIP (Common Industrial Protocol) network packets, the length parameter is inconsistently typed…EPSS 0.63%9.1CVE-2026-51537Opener project opener out-of-bounds read vulnerabilityEIPStackGroup OpENer 2.3.0 (commit 76b95cf) has an out-of-bounds read issue in Connection Manager handling of ForwardOpen requests when processing sh…EPSS 0.65%9.1CVE-2026-51541Opener project opener out-of-bounds read vulnerabilityOpENer 2.3.0 (commit 76b95cf) has an out-of-bounds read issue in CIP message parsing when handling malformed explicit requests with a forged EPath si…EPSS 0.55%

Source: NIST National Vulnerability Database (record CVE-2026-51538), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.