CVE-2021-25666: Siemens Scalance w740 Firmware

Medium severity, CVSS 4.3. EPSS: 0.7% chance of exploitation in the next 30 days.

A vulnerability has been identified in SCALANCE W780 and W740 (IEEE 802.11n) family (All versions < V6.3). Sending specially crafted packets through the ARP protocol to an affected device could cause a partial denial-of-service, preventing the device to operate normally for a short period of time.

Affected products

• Siemens Scalance w740 Firmware: before 6.3 (fixed in 6.3)
• Siemens Scalance w780 Firmware: before 6.3 (fixed in 6.3)

Published 2021-02-09. Last modified 2026-06-17.