---
id: "CVE-2026-68906"
kind: "vulnerability"
aliases: ["CVE-2026-68906"]
title: "libIEC61850: malformed ACSE packet causes infinite loop or crash"
severity: "high"
cvss: 8.7
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["embedded", "energy", "iec-61850", "libiec61850", "package", "scada"]
not_affected_if: ["version-1.6.2-or-later"]
published_at: "2026-10-16T16:20:00+00:00"
first_seen_at: "2026-10-23T21:57:13+00:00"
updated_at: "2026-10-23T22:39:05+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68906", "first_seen_at": "2026-10-23T21:57:13+00:00"}]
---

# libIEC61850: malformed ACSE packet causes infinite loop or crash

A malformed association response (AARE) sent to libIEC61850 during connection setup makes the parser loop forever on the CPU, or read one byte before a buffer and abort the process. An unauthenticated remote peer can trigger it, so a client or server exposed to the network can be stalled or crashed.

_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 package manifest: unknown if the sources do not say which packages embed it.

## 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-2026-68906

## 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, parseUserInformation in src/mms/iso_acse/acse.c checks len for zero before validating the negative bufPos returned by BerDecoder_decodeLength for a truncated long-form length. The continue path therefore swallows the error, reads buffer[-1], resets parsing to the beginning, and repeats the same malformed state. An unauthenticated remote peer can send a malformed AARE PDU during association to cause an infinite CPU loop under a normal allocator or a one-byte out-of-bounds read and process abort when the preceding byte is inaccessible. This issue is fixed in version 1.6.2.

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