CVE-2017-6030: Schneider Electric Modicon m221 Firmware

Medium severity, CVSS 6.5. EPSS: 2.1% chance of exploitation in the next 30 days.

A predictable value range from previous values issue was discovered in Schneider Electric Modicon PLCs Modicon M221, firmware versions prior to Version 1.5.0.0, Modicon M241, firmware versions prior to Version 4.0.5.11, and Modicon M251, firmware versions prior to Version 4.0.5.11. The affected products generate insufficiently random TCP initial sequence numbers that may allow an attacker to predict the numbers from previous values. This may allow an attacker to spoof or disrupt TCP connections.

Affected products

• Schneider Electric Modicon m221 Firmware: up to and including 1.1.1.5
• Schneider Electric Modicon m241 Firmware: up to and including 4.0.3.20
• Schneider Electric Modicon m251 Firmware: up to and including 4.0.3.20

Published 2017-06-30. Last modified 2026-06-17.