# CVE-2026-66369: MZ Automation libiec61850 DoS in GOOSE parser

Source: https://junglewise.ai/threats/cve-2026-66369-mz-automation-libiec61850-dos-in-goose-parser  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-30. Updated: 2026-07-30  
License: CC BY 4.0 with a link back

CVE-2026-66369 · Severity: medium · CVSS 6.5 · Published 2026-07-30

A vulnerability exists in a widely used library for industrial power grid communication. An attacker on the local network can send a single malicious message to crash the software responsible for monitoring electrical equipment. This results in a denial-of-service, potentially disrupting the visibility and control of critical energy infrastructure.

## Quick answers

**Is CVE-2026-66369 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-66369 being exploited in the wild.

**How severe is CVE-2026-66369?** 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-2026-66369?** 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-2026-66369 attacked?** It is attacked from the adjacent network, in a software library.

**Am I affected by CVE-2026-66369?** 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 off-by-one boundary-handling flaw exists within the GOOSE parser component of libiec61850. The vulnerability is triggered when the parser incorrectly advances its internal buffer position while processing specific fields in a GOOSE message, leading to a heap out-of-bounds read (CWE-125). An unauthenticated attacker on the same Layer-2 network (process bus) can exploit this by sending a single crafted multicast frame. Successful exploitation reliably terminates the subscriber process, resulting in a denial-of-service. The issue is resolved in version 1.6.2.

## Affected products

- MZ Automation GmbH libiec61850 < 1.6.2

## Timeline

- 2026-07-30: disclosed
- 2026-07-30: advisory

## References

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