CVE-2023-51773

The vulnerability, classified as CWE-126 (buffer over-read), occurs when the APDU (Application Protocol Data Unit) decoding function of the BACnet protocol reads data beyond the boundaries of the allocated buffer. An attacker can send a specially crafted network packet that forces incorrect decoding, resulting in reading data outside the intended memory area. Since the attack vector is network-based and does not require authentication or user interaction, the vulnerability is particularly dangerous in OT/BAS (Building Automation Systems) environments.

An attacker can remotely read fragments of process memory (potentially exposing sensitive data) and cause the application to crash (denial of service). Both consequences are possible without any authentication.

BACnet Stack should be updated to version 1.3.2 or later, in which the bug has been fixed (commit c465412a as part of pull request #546). It is also recommended to restrict network access to devices using the BACnet Stack library only to trusted network segments.

BACnet Stack (bacnet-stack) in versions before 1.3.2, including version 1.3.1 and earlier.