CVE-2021-25666

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-02-09 · updated 2026-06-17
Weakness: CWE-770

Description

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

How to fix

Upgrade to a fixed version: Siemens Scalance W740 Firmware 6.3; Siemens Scalance W780 Firmware 6.3. Check the vendor advisory for mitigations.

References

https://cert-portal.siemens.com/productcert/pdf/ssa-686152.pdf
https://us-cert.cisa.gov/ics/advisories/icsa-21-040-07
https://cert-portal.siemens.com/productcert/pdf/ssa-686152.pdf
https://us-cert.cisa.gov/ics/advisories/icsa-21-040-07

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