CVE-2021-33720: Siemens Siprotec 5 With CPU Variant CP050

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

A vulnerability has been identified in SIPROTEC 5 relays with CPU variants CP050 (All versions < V8.80), SIPROTEC 5 relays with CPU variants CP100 (All versions < V8.80), SIPROTEC 5 relays with CPU variants CP300 (All versions < V8.80). Specially crafted packets sent to port 4443/tcp could cause a Denial-of-Service condition.

Affected products

• Siemens Siprotec 5 With CPU Variant CP050: before 8.80 (fixed in 8.80)
• Siemens Siprotec 5 With CPU Variant CP100: before 8.80 (fixed in 8.80)
• Siemens Siprotec 5 With CPU Variant CP300: before 8.80 (fixed in 8.80)

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