Is CVE-2026-66364 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-66364 being exploited in the wild.

How severe is CVE-2026-66364?

Medium severity, with a CVSS score of 6.5, published 30 July 2026.

Which products and versions are affected?

MZ Automation GmbH libiec61850 < 1.6.2.

Is there a fix for CVE-2026-66364?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-66364 attacked?

It is attacked from the adjacent network, in a software library.

Am I affected by CVE-2026-66364?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-66364: MZ Automation GmbH libiec61850 out-of-bounds read in GOOSE parser

Q: Is there a fix for CVE-2026-66364?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

Q: How is CVE-2026-66364 attacked?

It is attacked from the adjacent network, in a software library.

Q: Am I affected by CVE-2026-66364?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-66364 · Severity: medium · CVSS 6.5 · Published 2026-07-30

A vulnerability exists in a specialized communication library used in energy infrastructure and industrial control systems. An attacker on the local network can send a single malicious message that crashes the system's communication service. This results in a denial-of-service, potentially disrupting the monitoring and control of power grid equipment.

Quick answers

Is CVE-2026-66364 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-66364 being exploited in the wild.
How severe is CVE-2026-66364?: Medium severity, with a CVSS score of 6.5, published 30 July 2026.
Which products and versions are affected?: MZ Automation GmbH libiec61850 < 1.6.2.
Is there a fix for CVE-2026-66364?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-66364 attacked?: It is attacked from the adjacent network, in a software library.
Am I affected by CVE-2026-66364?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A boundary handling flaw exists in the GOOSE payload parser of libiec61850 before version 1.6.2. The vulnerability is triggered when an attacker-controlled inner element length exceeds its enclosing length within a Layer 2 multicast frame (EtherType 0x88B8). This leads to a one-byte heap out-of-bounds read (CWE-125). Exploitation reliably terminates the subscriber process, resulting in a denial-of-service condition. The attack requires no authentication but must be launched from the same local network segment (process bus). The issue is resolved in version 1.6.2.

Affected products

MZ Automation GmbH libiec61850 < 1.6.2

Timeline

2026-07-30: advisory
2026-07-30: disclosed

References

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