CVE-2021-25660: Siemens SIMATIC HMI Comfort Outdoor Panels 15" Firmware

High severity, CVSS 7.5. EPSS: 1% chance of exploitation in the next 30 days.

A vulnerability has been identified in SIMATIC HMI Comfort Outdoor Panels V15 7\" & 15\" (incl. SIPLUS variants) (All versions < V15.1 Update 6), SIMATIC HMI Comfort Outdoor Panels V16 7\" & 15\" (incl. SIPLUS variants) (All versions < V16 Update 4), SIMATIC HMI Comfort Panels V15 4\" - 22\" (incl. SIPLUS variants) (All versions < V15.1 Update 6), SIMATIC HMI Comfort Panels V16 4\" - 22\" (incl. SIPLUS variants) (All versions < V16 Update 4), SIMATIC HMI KTP Mobile Panels V15 KTP400F, KTP700, KTP700F, KTP900 and KTP900F (All versions < V15.1 Update 6), SIMATIC HMI KTP Mobile Panels V16 KTP400F, KTP700, KTP700F, KTP900 and KTP900F (All versions < V16 Update 4), SIMATIC WinCC Runtime Advanced V15 (All versions < V15.1 Update 6), SIMATIC WinCC Runtime Advanced V16 (All versions < V16 Update 4). SmartVNC has an out-of-bounds memory access vulnerability that could be triggered on the server side when sending data from the client, which could result in a Denial-of-Service condition.

Affected products

• Siemens SIMATIC HMI Comfort Outdoor Panels 15" Firmware: before 16 (fixed in 16); version 16 only; before 15.1 (fixed in 15.1); version 15.1 only
• Siemens SIMATIC HMI Comfort Outdoor Panels 7" Firmware: before 16 (fixed in 16); version 16 only; before 15.1 (fixed in 15.1); version 15.1 only
• Siemens SIMATIC HMI Comfort Panels 22" Firmware: before 16 (fixed in 16); version 16 only; before 15.1 (fixed in 15.1); version 15.1 only
• Siemens SIMATIC HMI Comfort Panels 4" Firmware: before 16 (fixed in 16); version 16 only; before 15.1 (fixed in 15.1); version 15.1 only
• Siemens SIMATIC HMI Ktp Mobile Panels KTP400F Firmware: before 16 (fixed in 16); version 16 only; before 15.1 (fixed in 15.1); version 15.1 only
• Siemens SIMATIC HMI Ktp Mobile Panels KTP700 Firmware: before 16 (fixed in 16); version 16 only; before 15.1 (fixed in 15.1); version 15.1 only
• Siemens SIMATIC HMI Ktp Mobile Panels KTP700F Firmware: before 16 (fixed in 16); version 16 only; before 15.1 (fixed in 15.1); version 15.1 only
• Siemens SIMATIC HMI Ktp Mobile Panels KTP900 Firmware: before 16 (fixed in 16); version 16 only; before 15.1 (fixed in 15.1); version 15.1 only
• Siemens SIMATIC HMI Ktp Mobile Panels KTP900F Firmware: before 16 (fixed in 16); version 16 only; before 15.1 (fixed in 15.1); version 15.1 only
• Siemens SIMATIC Wincc Runtime Advanced: before 16 (fixed in 16); version 16 only; before 15.1 (fixed in 15.1); version 15.1 only

Published 2021-05-12. Last modified 2026-06-17.