Is CVE-2026-19259 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-19259 being exploited in the wild.

How severe is CVE-2026-19259?

Medium severity, with a CVSS score of 5.3, published 8 August 2026.

Which products and versions are affected?

MZ Automation libIEC61850 up to 1.6.1.

Is there a fix for CVE-2026-19259?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-19259 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-19259?

Check whether you run MZ Automation libIEC61850 at an affected version. 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-2026-19259: MZ Automation libiec61850 heap buffer overflow in MmsMapping

CVE-2026-19259 · Severity: medium · CVSS 5.3 · Published 2026-08-08

MZ Automation libiec61850 is a library used by industrial control system (ICS) client applications to communicate with power grid and utility servers using the IEC 61850 protocol. A malicious or compromised server can send a specially crafted response that triggers a heap buffer overflow in the client, causing the application to crash and denying service to operators who rely on these systems for monitoring and control.

Technologies: MZ Automation libIEC61850. Vendors: MZ Automation.

Quick answers

Is CVE-2026-19259 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-19259 being exploited in the wild.
How severe is CVE-2026-19259?: Medium severity, with a CVSS score of 5.3, published 8 August 2026.
Which products and versions are affected?: MZ Automation libIEC61850 up to 1.6.1.
Is there a fix for CVE-2026-19259?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-19259 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-19259?: Check whether you run MZ Automation libIEC61850 at an affected version. 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

The vulnerability is a heap buffer over-read in the MmsMapping_varAccessSpecToObjectReference function (src/iec61850/common/iec61850_common.c, line 876) triggered by a malformed GetNamedVariableListAttributesResponse.itemId field. The vulnerable code assumes that decoded MMS names follow an internal LN$FC$... format and performs fixed-offset reads relative to the first '$' separator without validating the string length. When a malicious MMS server returns itemId="$" (two bytes: '$' and null terminator), the conversion routine reads past the allocated heap buffer. The attack is client-side, reachable during normal protocol operation (dataset directory enumeration), and requires network connectivity to a malicious or MITM-compromised MMS server. An attacker can cause denial of service by crashing libiec61850-based client applications. The project has not yet responded to the early disclosure.

Affected products

MZ Automation libiec61850 up to 1.6.1

Timeline

2026-08-08: disclosed: CVE-2026-19259 published
2026-08-08: other: Exploit proof-of-concept available

References

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