CVE-2021-27391: Siemens Apogee Mbc (ppc) (p2 Ethernet) Firmware

Critical severity, CVSS 9.8. EPSS: 3.4% chance of exploitation in the next 30 days.

A vulnerability has been identified in APOGEE MBC (PPC) (P2 Ethernet) (All versions >= V2.6.3), APOGEE MEC (PPC) (P2 Ethernet) (All versions >= V2.6.3), APOGEE PXC Compact (BACnet) (All versions < V3.5.3), APOGEE PXC Compact (P2 Ethernet) (All versions >= V2.8), APOGEE PXC Modular (BACnet) (All versions < V3.5.3), APOGEE PXC Modular (P2 Ethernet) (All versions >= V2.8), TALON TC Compact (BACnet) (All versions < V3.5.3), TALON TC Modular (BACnet) (All versions < V3.5.3). The web server of affected devices lacks proper bounds checking when parsing the Host parameter in HTTP requests, which could lead to a buffer overflow. An unauthenticated remote attacker could exploit this vulnerability to execute arbitrary code on the device with root privileges.

Affected products

• Siemens Apogee Mbc (ppc) (p2 Ethernet) Firmware: up to and including 2.6.3
• Siemens Apogee Mec (ppc) (p2 Ethernet) Firmware: up to and including 2.6.3
• Siemens Apogee Pxc Bacnet Automation Controller Firmware: before 3.5.3 (fixed in 3.5.3)
• Siemens Apogee Pxc Compact (p2 Ethernet) Firmware: up to and including 2.8
• Siemens Apogee Pxc Modular (bacnet) Firmware: before 3.5.3 (fixed in 3.5.3)
• Siemens Apogee Pxc Modular (p2 Ethernet) Firmware: up to and including 2.8
• Siemens Talon Tc Compact (bacnet) Firmware: before 3.5.3 (fixed in 3.5.3)
• Siemens Talon Tc Modular (bacnet) Firmware: before 3.5.3 (fixed in 3.5.3)

Published 2021-09-14. Last modified 2026-06-17.