---
id: "CVE-2026-48741"
kind: "vulnerability"
aliases: ["CVE-2026-48741"]
title: "libIEC61850: crafted MMS read request crashes server via NULL dereference"
severity: "high"
cvss: 7.5
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["c", "embedded", "energy", "iec61850", "libiec61850", "package", "scada"]
not_affected_if: ["libiec61850-1.6.2-or-later", "no-array-data-in-model"]
published_at: "2026-10-16T16:18:11+00:00"
first_seen_at: "2026-10-23T21:57:13+00:00"
updated_at: "2026-10-25T03:25:02+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-48741", "first_seen_at": "2026-10-23T21:57:13+00:00"}]
---

# libIEC61850: crafted MMS read request crashes server via NULL dereference

libIEC61850 prior to 1.6.2 mishandles alternate-access sub-array ranges in MMS Read requests, dereferencing a NULL pointer. A remote client can crash a server that exposes array data in its model.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the libIEC61850 version in your build or vendored source; affected versions are those before `1.6.2`.
- Look for an MMS server built from libIEC61850 that is reachable on TCP port 102 from untrusted networks.

## Fix

- Upgrade libIEC61850 to `1.6.2` or later.

## Timeline

- 2026-10-23T21:57:13+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-48741

## From the sources

libIEC61850 is an open-source implementation of IEC 61850 client and server protocols including MMS, GOOSE, Sampled Values, and R-Session. Prior to 1.6.2, alternateArrayAccess in src/mms/iso_mms/server/mms_read_service.c does not validate an alternate-access sub-array range when numberOfElements is greater than zero. An out-of-range MmsValue_getElement call returns NULL, and the sub-array branch passes that value to MmsValue_isDeletable, causing a NULL pointer dereference. A remote MMS Read request can therefore crash servers whose data models contain arrays, while the single-element error path handles the same invalid index safely. This issue is fixed in version 1.6.2.

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