CVE-2026-66720

MZ Automation libiec61850 Out-of-bounds Read

Published Jul 30, 2026 CVSS 4.0 · 7.1 High EPSS < 1% KEV · Not listed

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.

Analysis

Technical impact

The GOOSE subscriber in libiec61850 fails to validate the UTC timestamp field in unauthenticated IEC 61850 GOOSE messages. A malicious message that contains an undersized timestamp field can trigger a heap out‑of‑bounds read, causing the process to crash. The resulting crash creates a denial‑of‑service condition. This weakness is classified as CWE‑125.

Affected Systems

MZ Automation GmbH’s libiec61850 library is affected. All releases prior to the recommended 1.6.2 update are vulnerable.

Risk and Exploitability

The CVSS score of 7.1 indicates a high severity vulnerability. The EPSS score is < 1%, and the vulnerability is not in the CISA KEV catalog. A remote attacker who can inject crafted GOOSE frames onto the network can exploit the flaw without authentication, leading to service disruption.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

MZ Automation GmbH

libiec61850

unaffected

Version	Status	Constraints
`0`	affected	< 1.6.2
`1.6.2`	unaffected	—

No data.

Vendor Product Versions

Mz-automation

Libiec61850

Version	Status	Scheme	Platform
`[0,1.6.2)`	affected	generic	—
`1.6.2`	unaffected	semver	—

Remediation

Vendor Solution

MZ Automation GmbH recommends that users update to version 1.6.2.

OpenCVE Recommended Actions

Apply the vendor‑supplied patch to update libiec61850 to version 1.6.2
If patch deployment is delayed, block or filter IEC 61850 GOOSE traffic (EtherType 0x88B8) on the network perimeter to prevent malicious frames from reaching the subscriber
Monitor system logs for unexpected crashes or DDoS patterns that may indicate exploitation attempts

Generated by OpenCVE AI on August 3, 2026 at 10:21 UTC.

Tracking

Advisories

No advisories available

Metrics

Attack Vector Adjacent Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Adjacent Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.285% probability within 30 days)

Exploitation none

Automatable no

Technical Impact partial

References

Link	Providers
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

History

Jul 31, 2026 4:30 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Jul 31, 2026 12:45 AM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Mz-automation Mz-automation libiec61850
Vendors & Products		Mz-automation Mz-automation libiec61850

Jul 30, 2026 11:15 PM Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
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.
Title		MZ Automation libiec61850 Out-of-bounds Read
Weaknesses		CWE-125
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
Metrics		cvssV3_1 `{'score': 6.5, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}` cvssV4_0 `{'score': 7.1, 'vector': 'CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}`