CVE-2021-25659: Siemens Automation License Manager

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

A vulnerability has been identified in Automation License Manager 5 (All versions), Automation License Manager 6 (All versions < V6.0 SP9 Update 2). Sending specially crafted packets to port 4410/tcp of an affected system could lead to extensive memory being consumed and as such could cause a denial-of-service preventing legitimate users from using the system.

Affected products

• Siemens Automation License Manager: from 5.0.0, before 6.0.9 (fixed in 6.0.9)

Published 2021-08-10. Last modified 2026-06-17.