---
id: "CVE-2026-45265"
page: "https://infrastack.ai/live/CVE-2026-45265"
kind: "vulnerability"
aliases: ["CVE-2026-45265"]
title: "BACnet Stack: crafted file-read request overflows server stack buffer"
severity: "high"
cvss: 8.2
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["bacnet", "building-automation", "c", "embedded", "package"]
not_affected_if: ["client-only", "no-record-access-mode"]
published_at: "2026-11-12T20:18:38+00:00"
first_seen_at: "2026-11-12T20:40:26+00:00"
updated_at: "2026-11-12T20:42:05+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45265", "first_seen_at": "2026-11-12T20:40:26+00:00"}]
exploit_sources: []
---

# BACnet Stack: crafted file-read request overflows server stack buffer

Link for people: https://infrastack.ai/live/CVE-2026-45265 (this .md is for agents)

BACnet Stack is a C library implementing the BACnet building-automation protocol for embedded devices. A crafted Atomic-Read-File request with a large RecordCount makes the server write past a stack buffer, which can let an attacker crash the server or run code on it.

_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; affected versions are those before `1.4.4` and `1.5.1`.
- Look for the Atomic-Read-File record access handling in your server code, which is the path that triggers the bug.

## Fix

- Move to `1.4.4` or `1.5.1` or later, per the patched versions in the advisory.

## Timeline

- 2026-11-12T20:40:26+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-45265

## Documents

- [advisory] Vendor advisory: github.com https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-v3gx-mwrp-xvh5

## 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, there is a stack-based out-of-bounds write / stack-buffer-overflow in bacnet-stack when the server processes a malicious Atomic-Read-File request in record access mode. The bug is triggered on the real server side. A crafted request can set an excessively large RecordCount, which is later used as the loop bound for writing record data into a stack-allocated BACNET_ATOMIC_READ_FILE_DATA data structure. However, the stack object only has space for one fileData element. When the loop reaches i = 1, the code computes &data->fileData[1], which is already out of bounds, and the resulting invalid pointer is passed down to memmove(), causing a stack-buffer-overflow. This issue has been patched in versions 1.4.4 and 1.5.1.

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