CVE-2025-40556: Siemens Bacnet Atec 550-440

Medium severity, CVSS 6.5. EPSS: 0.3% chance of exploitation in the next 30 days.

A vulnerability has been identified in BACnet ATEC 550-440 (All versions), BACnet ATEC 550-441 (All versions), BACnet ATEC 550-445 (All versions), BACnet ATEC 550-446 (All versions). Affected devices improperly handle specific incoming BACnet MSTP messages. This could allow an attacker residing in the same BACnet network to send a specially crafted MSTP message that results in a denial of service condition of the targeted device. A power cycle is required to restore the device's normal operation.

Affected products

• Siemens Bacnet Atec 550-440: any version
• Siemens Bacnet Atec 550-441: any version
• Siemens Bacnet Atec 550-445: any version
• Siemens Bacnet Atec 550-446: any version

Published 2025-05-13. Last modified 2026-06-17.