How severe is CVE-2026-51536?

CVE-2026-51536 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-2026-51536 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-2026-51536?

CVE-2026-51536 affects Opener Project Opener. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-51536?

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-2026-51536 published?

CVE-2026-51536 was published on 2026-07-13 and last updated on 2026-08-11.

CVE-2026-51536

CVE-2026-51536 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-190.

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-190
Affected product: Opener Project Opener
Published: 2026-07-13
Last modified: 2026-08-11

Description

In OpENer 2.3.0 (commit 76b95cf) when parsing incoming CIP (Common Industrial Protocol) network packets, the length parameter is inconsistently typed across the call stack. Specifically, an upstream length calculated as an int is passed to a downstream function that expects an EipInt16 (a 16-bit signed integer). If a maliciously crafted packet with specific length fields is processed, the length parameter can overflow or be truncated into a negative value. This negative length bypasses subsequent bounds checking (due to signed/unsigned comparison issues) and is ultimately used in memory operations, leading to a Stack Buffer Overflow when reading data in DecodePaddedEPath.

Frequently asked questions

What is CVE-2026-51536?: In OpENer 2.3.0 (commit 76b95cf) when parsing incoming CIP (Common Industrial Protocol) network packets, the length parameter is inconsistently typed across the call stack. Specifically, an upstream length calculated as an int is passed to a downstream function that expects an EipInt16 (a 16-bit signed integer). If a maliciously crafted packet with specific length fields is processed, the length parameter can overflow or be truncated into a negative value. This negative length bypasses subsequent bounds checking (due to signed/unsigned comparison issues) and is ultimately used in memory operations, leading to a Stack Buffer Overflow when reading data in DecodePaddedEPath.
How severe is CVE-2026-51536?: CVE-2026-51536 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-2026-51536 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-2026-51536?: CVE-2026-51536 affects Opener Project Opener. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-51536?: 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-2026-51536 published?: CVE-2026-51536 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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