# CVE-2026-63550: MZ Automation GmbH libiec61850 heap out-of-bounds read in MMS BER decoder

Source: https://junglewise.ai/threats/cve-2026-63550-mz-automation-gmbh-libiec61850-heap-out-of-bounds-read-in-mms-ber  
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-2026-63550 · Severity: medium · CVSS 6.5 · Published 2026-07-30

A vulnerability exists in a library used for communication in energy and industrial control systems. An attacker with access to the network could send a specially crafted message to a device using this library, causing the communication service to crash. This results in a denial-of-service, potentially disrupting the monitoring or control of critical infrastructure.

## Quick answers

**Is CVE-2026-63550 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-63550 being exploited in the wild.

**How severe is CVE-2026-63550?** 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-2026-63550?** A patch was published on 2026-07-30: Vendor recommends updating to version 1.6.2 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-63550 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-63550?** 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

A heap out-of-bounds read vulnerability (CWE-125) exists in the MMS BER decoder of libiec61850. The flaw is located in the boundary-handling logic when processing specific fields within confirmed-request messages. An attacker can exploit this by sending a crafted BER-encoded element over an established MMS session (TCP port 102). This causes the decoder to incorrectly advance its internal read position, leading to an out-of-bounds read that crashes the MMS handling process. The vulnerability is addressed 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: CVE-2026-63550 published
- 2026-07-30: patched: Vendor recommends updating to version 1.6.2

## 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)