---
id: "CVE-2026-49990"
page: "https://infrastack.ai/live/CVE-2026-49990"
kind: "vulnerability"
aliases: ["CVE-2026-49990"]
title: "BACnet Stack: unchecked file offset lets remote requests crash or corrupt memory"
severity: "high"
cvss: 8.6
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["bacnet", "building-automation", "c", "embedded", "package"]
not_affected_if: ["no-file-stream-access", "outside-affected-version-range"]
published_at: "2026-11-13T16:19:01+00:00"
first_seen_at: "2026-11-13T16:47:34+00:00"
updated_at: "2026-11-13T16:48:23+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-49990", "first_seen_at": "2026-11-13T16:47:34+00:00"}]
exploit_sources: []
---

# BACnet Stack: unchecked file offset lets remote requests crash or corrupt memory

Link for people: https://infrastack.ai/live/CVE-2026-49990 (this .md is for agents)

BACnet Stack is a C library implementing the BACnet building-automation protocol for embedded devices. A signed file start position in AtomicReadFile and AtomicWriteFile requests is not validated tightly enough, so a crafted request can crash the process, read adjacent memory, or write out of bounds into heap memory.

_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 dependency manifest; affected versions are 1.4.2 up to but not including `1.4.5`, and 1.5.0 up to but not including `1.5.1`.
- Check whether the device exposes BACnet stream file access (AtomicReadFile or AtomicWriteFile) on a reachable network.

## Fix

- Move to `1.4.5` on the 1.4 line.
- Move to `1.5.1` on the 1.5 line.

## Timeline

- 2026-11-13T16:47:34+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-49990

## Documents

- [advisory] Vendor advisory: github.com https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-8759-hx7g-94qx

## From the sources

BACnet Stack is a BACnet open source protocol stack C library for embedded systems. From versions 1.4.2 to before 1.4.5, and 1.5.0 to before 1.5.1, a signed fileStartPosition taken from AtomicReadFile and AtomicWriteFile stream-access requests is not validated tightly enough before it reaches the RAM file backends. Practical impact includes: reliable denial of service via process crash, out-of-bounds read that may expose adjacent memory contents, or out-of-bounds write that may corrupt heap memory and destabilize the process. This issue has been patched in versions 1.4.5 and 1.5.1.

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