CVE-2026-66360

MZ Automation libiec61850 Out-of-bounds Read

Published Jul 30, 2026 CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Description

The ISO Presentation layer contains a flaw in the handling of specific
parameters during normal mode negotiation. A missing length check in the
processing of the encoded presentation data allows an attacker
controlled field with a zero length value to trigger a bounded heap over
read. This condition occurs before MMS session establishment, a crafted
TCP/102 connection attempt can trigger the issue. The resulting over
read causes the process to terminate, leading to a denial of service
condition.

Analysis

Technical impact

The issue resides in the ISO Presentation layer of MZ Automation GmbH’s libiec61850 library. During normal mode negotiation, a missing length check while decoding presented data allows an attacker to supply a field with a zero length, which triggers a bounded heap overread before the MMS session is established. The overread causes the process to terminate, resulting in a denial of service for the affected system.

Affected Systems

The vulnerability affects the libiec61850 library distributed by MZ Automation GmbH. No specific version range is listed, but the vendor recommends updating to version 1.6.2 to resolve the flaw.

Risk and Exploitability

The CVSS score is 8.7, indicating a high severity vulnerability. EPSS score is < 1%, and the flaw is not listed in the CISA catalog. Attacks occur remotely via a crafted TCP connection to port 102 before the MMS session begins. Exploitation requires network reachability to the target device and does not provide information disclosure or privilege escalation; the impact is limited to causing the associated process to crash and deny service.

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

Update the libiec61850 library to version 1.6.2 as recommended by MZ Automation.
If an upgrade cannot be applied immediately, block inbound TCP traffic on port 102 or isolate devices using the library from untrusted networks to prevent remote session initiation.
Apply or develop a patched version of the library that includes bounds checks for encoded presentation data to prevent out‑of‑bounds reads.
Set up monitoring of application logs for abnormal termination events that may indicate exploitation attempts.

Generated by OpenCVE AI on August 3, 2026 at 10:22 UTC.

Tracking

Advisories

No advisories available

Metrics

Attack Vector 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 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% (0.488% probability within 30 days)

Exploitation none

Automatable yes

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': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Jul 31, 2026 12:15 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 10:45 PM Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		The ISO Presentation layer contains a flaw in the handling of specific parameters during normal mode negotiation. A missing length check in the processing of the encoded presentation data allows an attacker controlled field with a zero length value to trigger a bounded heap over read. This condition occurs before MMS session establishment, a crafted TCP/102 connection attempt can trigger the issue. The resulting over read causes the process to terminate, leading to 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': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}` cvssV4_0 `{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}`