CVE-2026-66720: MZ Automation libiec61850 Out-of-bounds Read

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-30 · updated 2026-09-03
Weakness: CWE-125

Description

The GOOSE subscriber component improperly validates the UTC timestamp field in unauthenticated IEC 61850 GOOSE (EtherType 0x88B8) Layer-2 multicast messages. A specially crafted GOOSE frame containing an undersized timestamp field can trigger a heap out-of-bounds read during message processing, causing the process to crash and resulting in a denial-of-service condition.

Affected products

mz-automation libiec61850: before 1.6.2 — fixed in 1.6.2

How to fix

Upgrade to a fixed version: mz-automation libiec61850 1.6.2. Check the vendor advisory for mitigations.

References

https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-211-10.json
https://www.cisa.gov/news-events/ics-advisories/icsa-26-211-10

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