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Vulnerability record · CVE-2021-21777 · published 17 June 2021

CVE-2021-21777: Opener project opener out-of-bounds read vulnerability

Opener Project · Opener

An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer 2.3 and development commit 8c73bf3. A specially crafted network request can lead to an out-of-bounds read.

10.0 CVSS 3.1 Critical EPSS 1.7% · top 24.2% CWE-125 · Out-of-bounds read
10.0CVSS 3.1 base score, v2 9.4
1.7%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer 2.3 and development commit 8c73bf3. A specially crafted network request can lead to an out-of-bounds read.

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

Affected products

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

References

LinkTags
https://talosintelligence.com/vulnerability_reports/TALOS-2021-1234 ExploitThird Party Advisory
https://talosintelligence.com/vulnerability_reports/TALOS-2021-1234 ExploitThird Party Advisory

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Related vulnerabilities

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

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-2026-51538Opener project opener improper access control vulnerabilityEIPStackGroup OpENer 2.3.0 (commit 76b95cf) suffers from an Incorrect Access Control vulnerability in its handling of encapsulation sessions. When th…EPSS 0.52%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-2021-21777), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.