CVE-2026-66349 PUBLISHED

MZ Automation libiec61850 Out-of-bounds Read

Assigner: icscert
Reserved: 27.07.2026 Published: 30.07.2026 Updated: 30.07.2026

The MMS server connection handler contains a flaw in its processing of BER-encoded request data. When an MMS confirmed request PDU containing an extended BER tag is received over an established session, the decoder may advance its internal buffer incorrectly due to a missing bounds check. This results in a one byte heap out-of-bounds read and causes the MMS service process to terminate, leading to a denial-of-service condition.

CVSS Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS Score: 6.5

Attack Vector	Adjacent Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	High

CVSS 3.1

CVSS Vector: CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS Score: 6.9

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Adjacent	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	High	Availability	None
Privileges Required	Low
User Interaction	None

CVSS 4.0

Product Status

Vendor	MZ Automation GmbH
Product	libiec61850
Versions	Default: unaffected affected from 0 to 1.6.2 (excl.) Version 1.6.2 is unaffected

Solutions

MZ Automation GmbH recommends that users update to version 1.6.2.

Credits

Arun Babu of Central Power Research Institute reported this vulnerability to CISA. finder

References

Problem Types

CWE-125 CWE