# CVE-2026-56758: MZ Automation GmbH libiec61850 out-of-bounds read in ACSE layer

Source: https://junglewise.ai/threats/cve-2026-56758-mz-automation-gmbh-libiec61850-out-of-bounds-read-in-acse-layer  
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-2026-56758 · Severity: medium · CVSS 6.5 · Published 2026-07-30

A vulnerability exists in libiec61850, a software library used in the energy sector to facilitate communication between industrial control devices. An attacker on the same local network could send a specially crafted message during the connection process to crash the service. This would result in a denial-of-service, potentially disrupting power grid monitoring or control operations.

## Quick answers

**Is CVE-2026-56758 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-56758 being exploited in the wild.

**How severe is CVE-2026-56758?** 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-2026-56758?** 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-2026-56758 attacked?** It is attacked from the adjacent network, in a software library.

**Am I affected by CVE-2026-56758?** 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 (CWE-125) exists in the ACSE (Association Control Service Element) layer of libiec61850. The flaw occurs during the parsing of AARQ (Associate Request) Protocol Data Units (PDUs) when establishing a Manufacturing Message Specification (MMS) connection. Specifically, when parsing fields within the 'calling AP title', the parser fails to properly validate attacker-controlled length values of zero or one. This causes the parser to read past the end of a heap buffer, resulting in a process crash and denial-of-service. The attack can be launched by an unauthenticated attacker on the adjacent network. The issue is resolved in version 1.6.2.

## Affected products

- MZ Automation GmbH libiec61850 < 1.6.2

## Timeline

- 2026-07-30: advisory: CISA ICSA-26-211-10 published
- 2026-07-30: disclosed: NVD publication date

## 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)