What is the CVSS score of EUVD-2026-40246?

EUVD-2026-40246 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 0.2%.

Which versions of OpENer are affected by EUVD-2026-40246?

EIPStackGroup OpENer, an open-source EtherNet/IP stack widely deployed in industrial automation and ICS/SCADA environments, contains a critical remote denial-of-service vulnerability (CVE-2026-51221,…

How to fix or mitigate EUVD-2026-40246?

Within 24 hours: Inventory all systems and applications utilizing EIPStackGroup OpENer; prioritize production ICS/SCADA deployments and critical process systems. Within 7 days: Implement network segmentation to restrict access to EtherNet/IP services from untrusted networks; disable EtherNet/IP protocol where operationally feasible; deploy firewall and IDS rules to detect and block malformed Common Packet Format (CPF) traffic targeting vulnerable components. Within 30 days: Establish continuous monitoring of vendor advisories and CVE databases for patch release; conduct formal risk assessment comparing operational cost of elevated monitoring versus potential DoS impact; implement application-level access controls and logging on systems that cannot be isolated.

OpENer EUVD-2026-40246

| CVE-2026-51221 HIGH

Improper Access Control (CWE-284)

2026-06-29 mitre

GHSA-p26f-vx3f-455g

Authentication Bypass Buffer Overflow Denial Of Service N A

7.5

CVSS 3.1 · Vendor: mitre

Severity by source

Vendor (mitre) PRIMARY

7.5 HIGH

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

vuln.today AI

7.5 HIGH

Unauthenticated, low-complexity network packet (AV:N/AC:L/PR:N/UI:N) crashes the stack with availability-only impact (A:H), no confidentiality or integrity effect.

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

4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (mitre).

CVSS VectorVendor: mitre

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

Analysis Generated

Jun 30, 2026 - 16:30 vuln.today

CVSS changed

Jun 30, 2026 - 14:22 NVD

7.5 (HIGH)

CVE Published

Jun 29, 2026 - 00:00 cve.org

UNKNOWN (no severity yet)

DescriptionCVE.org

A buffer overflow in the Get_Attribute_List function of EIPStackGroup OpENer commit 76b95c allows attackers to cause a Denial of Service (DoS) via supplying a crafted Common Packet Format (CPF) packet.

AnalysisAI

Denial of service in EIPStackGroup OpENer (commit 76b95c), an open-source EtherNet/IP stack, allows remote attackers to crash the device by sending a crafted Common Packet Format (CPF) packet that triggers a buffer overflow in the Get_Attribute_List handler. The flaw is network-reachable without authentication or user interaction (CVSS 7.5, availability-only impact), and SSVC indicates proof-of-concept exploit code exists and that exploitation is automatable. EPSS is low (0.17%, 7th percentile) and the CVE is not on CISA KEV, so there is no public evidence of active exploitation yet.

Technical ContextAI

OpENer is a widely-referenced open-source implementation of the EtherNet/IP and CIP (Common Industrial Protocol) stack used in embedded industrial automation devices, PLCs, and OT gateways. The vulnerable code path is the CIP Get_Attribute_List service, which parses attribute requests carried inside the Common Packet Format (CPF) - the encapsulation structure EtherNet/IP uses to wrap CIP messages over TCP/UDP port 44818/2222. The reported root cause is a buffer overflow (the input data classifies it under Buffer Overflow and Denial Of Service tags); the assigned CWE-284 (Improper Access Control) appears mismatched to the described memory-safety defect, which is more accurately a buffer overflow class (e.g. CWE-787/CWE-120). Because CIP requests are processed before any strong validation, a malformed attribute-count or length field in the CPF packet drives an out-of-bounds access, corrupting memory and crashing the stack.

RemediationAI

No vendor-released patch or tagged fixed version is identified at time of analysis - the references point only to the OpENer repository and to GitHub issue #567, not to a released patch or merged commit, so remediation currently means tracking that issue for a fix and rebuilding firmware once an upstream commit lands. As compensating controls, restrict network access to EtherNet/IP services (TCP/UDP 44818 and UDP 2222) so only trusted automation hosts can reach affected devices, ideally via dedicated OT VLAN segmentation and a firewall allowlist - this is the most effective mitigation but requires inventorying legitimate CIP clients to avoid breaking polling/scanning traffic. Where feasible, place devices behind an EtherNet/IP-aware deep-packet-inspection firewall to drop malformed CPF packets, and monitor for unexpected device resets as a detection signal. Avoid exposing these devices to the internet or IT networks entirely. Validate any custom integration by reviewing the Get_Attribute_List parsing path against issue #567 before redeploying.