CVE-2026-66349

MEDIUM 6.5

MZ Automation libiec61850 Out-of-bounds Read

CVSS Score

6.5

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-125
Vendor	mz automation gmbh
Product	libiec61850
Published	Jul 30, 2026

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CVSS v3 Breakdown

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

Attack Vector

Adjacent

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

MZ Automation GmbH / libiec61850

0 < 1.6.2

References

NVD ↗ CVE.org ↗ EPSS Data ↗

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

Credits

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