CVE-2026-47258 in Bacnet Stack
Summary
by MITRE • 11/12/2026
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to versions 1.4.4, 1.5.1, and 1.6.0, a stack-based out-of-bounds write exists in the Notification Class object implementation when handling AddListElement for the recipient-list property. This issue has been patched in versions 1.4.4, 1.5.1, and 1.6.0.
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Analysis
by VulDB Data Team • 11/12/2026
The BACnet Stack is a widely utilized open-source C library designed to implement the Building Automation and Control Networks protocol for embedded systems. This stack facilitates communication between devices in smart buildings, such as HVAC controllers, access control panels, and environmental sensors. A critical security flaw was identified within the Notification Class object implementation of this library prior to versions 1.4.4, 1.5.1, and 1.6.0. The vulnerability manifests specifically when processing AddListElement operations targeting the recipient-list property. This function is responsible for managing lists of devices or entities that should receive notifications regarding specific events within the building automation network.
The technical nature of this flaw is a stack-based out-of-bounds write, which falls under CWE-787 in the Common Weakness Enumeration taxonomy. During the execution of AddListElement, the library fails to adequately validate input parameters before writing data to memory locations on the call stack. This lack of boundary checking allows an attacker who can inject maliciously crafted BACnet messages into the network to write data beyond the allocated buffer space. In C programming languages, such as those used in this embedded system implementation, out-of-bounds writes are particularly dangerous because they do not just corrupt application state but can overwrite adjacent memory structures including return addresses and function pointers stored on the stack.
The operational impact of this vulnerability is severe due to its potential for remote code execution. An attacker positioned within the same network segment as a vulnerable BACnet device could exploit this flaw by sending specially crafted packets that trigger the out-of-bounds write condition. By carefully crafting the payload, an adversary can overwrite critical stack data with shellcode or control flow hijacking instructions. This effectively allows for arbitrary code execution on the embedded device running the affected BACnet Stack version. Given that many building automation systems operate in isolated networks but are increasingly connected to corporate IT infrastructure or the internet via gateways, successful exploitation could serve as an initial access vector into broader organizational networks.
This vulnerability aligns with MITRE ATT&CK technique T1203, which covers Exploitation for Client Execution, and potentially T1496 if used in a targeted attack scenario to disrupt building operations. The flaw highlights the risks associated with using open-source components in safety-critical infrastructure without rigorous security auditing. Developers of embedded systems often prioritize functionality over memory safety checks due to resource constraints, leading to common pitfalls like buffer overflows.
Mitigation strategies primarily involve upgrading the BACnet Stack library to version 1.4.4, 1.5.1, or later versions where this issue has been patched by implementing proper bounds checking during list element addition operations. For organizations unable to immediately patch their systems, network segmentation is recommended to isolate building automation networks from general corporate traffic. Additionally, deploying intrusion detection systems capable of inspecting BACnet protocol payloads can help identify and block malicious packets attempting to exploit the AddListElement function. Regular security assessments and code reviews focusing on memory safety in C-based embedded libraries are essential practices to prevent similar vulnerabilities in future deployments.