CVE-2026-66720

EUVD-2026-51359
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
icscertCNA
6.5 MEDIUM
ADJACENT_NETWORK
LOW
NONE
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 7%
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mz-automationlibiec61850
𝑥
< 1.6.2
CNA
Common Weakness Enumeration
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