---
id: "CVE-2026-46674"
page: "https://infrastack.ai/live/CVE-2026-46674"
kind: "vulnerability"
aliases: ["CVE-2026-46674"]
title: "BACnet Stack: out-of-bounds read in AtomicWriteFile record handling"
severity: "high"
cvss: 7.5
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["bacnet", "building-automation", "embedded", "package"]
not_affected_if: ["no-atomicwritefile-service", "patched-version"]
published_at: "2026-11-12T20:18:39+00:00"
first_seen_at: "2026-11-12T20:40:26+00:00"
updated_at: "2026-11-12T20:42:10+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-46674", "first_seen_at": "2026-11-12T20:40:26+00:00"}]
exploit_sources: []
---

# BACnet Stack: out-of-bounds read in AtomicWriteFile record handling

Link for people: https://infrastack.ai/live/CVE-2026-46674 (this .md is for agents)

BACnet Stack is a C library for BACnet building-automation devices. A mismatch between an externally supplied record count and a fixed-size internal array lets an attacker read memory outside that array.

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

## How to check

- Check the bacnet-stack version in your build or vendored source, for example with `grep -i version` on the bacnet-stack source tree
- Confirm whether your device or application uses the AtomicWriteFile service (BACNET_ATOMIC_WRITE_FILE_DATA)

## Fix

- bacnet-stack: move to `1.4.4` or `1.5.1`, the patched versions named in the advisory

## Timeline

- 2026-11-12T20:40:26+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-46674

## Documents

- [advisory] Vendor advisory: github.com https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-8384-pwhh-cxjh

## From the sources

BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to versions 1.4.4 and 1.5.1, an out-of-bounds read vulnerability exists in bacnet-stack's AtomicWriteFile record-access path. The bug is caused by a mismatch between an externally controlled returnedRecordCount field and the fixed-size internal fileData[] array used by BACNET_ATOMIC_WRITE_FILE_DATA. This issue has been patched in versions 1.4.4 and 1.5.1.

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_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_