Is CVE-2026-65421 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-65421 being exploited in the wild.

How severe is CVE-2026-65421?

Medium severity, with a CVSS score of 6.5, published 30 July 2026.

Which products and versions are affected?

MZ Automation GmbH libiec61850 < 1.6.2.

Is there a fix for CVE-2026-65421?

A patch was published on 2026-07-30. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-65421 attacked?

It is attacked from the adjacent network, in a software library.

Am I affected by CVE-2026-65421?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-65421: MZ Automation libiec61850 heap out-of-bounds read in MMS BER decoder

Q: Is there a fix for CVE-2026-65421?

A patch was published on 2026-07-30. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is CVE-2026-65421 attacked?

It is attacked from the adjacent network, in a software library.

Q: Am I affected by CVE-2026-65421?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-65421 · Severity: medium · CVSS 6.5 · Published 2026-07-30

MZ Automation libiec61850 is a software library used in the energy sector to implement communication protocols for electrical substation automation. A vulnerability in how the library handles specific data messages allows an attacker on the same local network to crash the service. This results in a denial-of-service condition, potentially disrupting the monitoring and control of critical power infrastructure.

Quick answers

Is CVE-2026-65421 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-65421 being exploited in the wild.
How severe is CVE-2026-65421?: Medium severity, with a CVSS score of 6.5, published 30 July 2026.
Which products and versions are affected?: MZ Automation GmbH libiec61850 < 1.6.2.
Is there a fix for CVE-2026-65421?: A patch was published on 2026-07-30. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-65421 attacked?: It is attacked from the adjacent network, in a software library.
Am I affected by CVE-2026-65421?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An out-of-bounds read vulnerability exists in the MMS BER decoder component of libiec61850. The flaw is located in the decoding logic for fixed-width Basic Encoding Rules (BER) fields, specifically booleans and integers. The decoder fails to validate attacker-supplied length values, leading to a read past the end of a heap buffer. An unauthenticated attacker on the adjacent network can exploit this by sending a specially crafted message, causing the MMS service process to terminate and resulting in a denial-of-service (DoS). The vulnerability is addressed in version 1.6.2.

Affected products

MZ Automation GmbH libiec61850 < 1.6.2

Timeline

2026-07-30: advisory
2026-07-30: patched

References

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