How severe is CVE-2026-51537?

CVE-2026-51537 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.

Is CVE-2026-51537 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (40th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-51537?

CVE-2026-51537 affects Opener Project Opener. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-51537?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2026-51537 published?

CVE-2026-51537 was published on 2026-07-13 and last updated on 2026-08-11.

CVE-2026-51537

CVE-2026-51537 is a critical-severity vulnerability in Opener Project Opener with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
EPSS exploit prediction: 0% (40th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Opener Project Opener
Published: 2026-07-13
Last modified: 2026-08-11

Description

EIPStackGroup OpENer 2.3.0 (commit 76b95cf) has an out-of-bounds read issue in Connection Manager handling of ForwardOpen requests when processing short malformed packets. An attacker can send a valid ENIP outer frame carrying a malformed CIP ForwardOpen/LargeForwardOpen request, causing the parser to continue reading fields even when request data is insufficient. This issue is remotely triggerable via network traffic and does not require authentication.

Frequently asked questions

What is CVE-2026-51537?: EIPStackGroup OpENer 2.3.0 (commit 76b95cf) has an out-of-bounds read issue in Connection Manager handling of ForwardOpen requests when processing short malformed packets. An attacker can send a valid ENIP outer frame carrying a malformed CIP ForwardOpen/LargeForwardOpen request, causing the parser to continue reading fields even when request data is insufficient. This issue is remotely triggerable via network traffic and does not require authentication.
How severe is CVE-2026-51537?: CVE-2026-51537 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.
Is CVE-2026-51537 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (40th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-51537?: CVE-2026-51537 affects Opener Project Opener. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-51537?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-51537 published?: CVE-2026-51537 was published on 2026-07-13 and last updated on 2026-08-11.

References

Affected products (1)

cpe:2.3:a:opener_project:opener:2.3.0:*:*:*:*:*:*:*

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