Which versions of Libiec61850 are affected by CVE-2026-50039?

A critical denial-of-service vulnerability in MZ Automation's libiec61850 library (CVE-2026-50039, CVSS 8.7) allows unauthenticated remote attackers to crash IEC 61850 MMS servers deployed in…

How to fix or mitigate CVE-2026-50039?

Within 24 hours, identify all systems running libiec61850 in your environment and map network exposure; determine which instances are accessible from untrusted networks or the internet and notify incident response and operational technology teams of the remote unauthenticated denial-of-service risk. Within 7 days, implement firewall rules to restrict IEC 61850 MMS protocol access to only authorized control systems, deploy network monitoring to detect anomalous Read Requests or buffer overflow indicators, and test existing redundancy or failover mechanisms to ensure they minimize impact of potential service crashes. Within 30 days, contact MZ Automation for patch status and timeline, evaluate alternative IEC 61850 protocol implementations from other vendors as contingency options, and document your compensating controls in your operational technology risk register.

Libiec61850 CVE-2026-50039

Q: What is the CVSS score of CVE-2026-50039?

CVE-2026-50039 has a CVSS 4.0 base score of 8.7 (High). CVSS 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.3%.

EUVD-2026-48428 HIGH

Stack-based Buffer Overflow (CWE-121)

2026-07-23 icscert

GHSA-mv2j-6f62-xx62

Stack Overflow Buffer Overflow Libiec61850

8.7

CVSS 4.0 · Vendor: icscert

Severity by source

Vendor (icscert) PRIMARY

8.7 HIGH

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

7.5 HIGH

Remote unauthenticated MMS Read Request (AV:N/AC:L/PR:N/UI:N) with confirmed impact limited to a crash, so A:H and C:N/I:N despite theoretical memory-corruption potential.

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

4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (icscert).

CVSS VectorVendor: icscert

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Analysis Updated

Jul 23, 2026 - 21:29 vuln.today

v2 (cvss_changed)

Re-analysis Queued

Jul 23, 2026 - 21:23 vuln.today

cvss_changed

CVSS changed

Jul 23, 2026 - 21:23 NVD

7.5 (HIGH) 8.7 (HIGH)

Analysis Generated

Jul 23, 2026 - 21:16 vuln.today

CVE Published

Jul 23, 2026 - 20:32 cve.org

HIGH 7.5

DescriptionCVE.org

The affected product is vulnerable to a stack-based buffer overflow, which may allow an attacker to cause a memory corruption via a Read Request.

AnalysisAI

Denial of service in MZ Automation's libiec61850 library allows remote unauthenticated attackers to corrupt memory by sending a crafted Read Request, triggering a stack-based buffer overflow (CWE-121). The flaw affects the IEC 61850 MMS server implementation used in power-grid and industrial automation devices, and was disclosed via a CISA ICS advisory (ICSA-26-204-06). No public exploit is identified at time of analysis, and the vendor CVSS 4.0 vector scores only availability impact, indicating a service crash rather than confirmed code execution.