What’s Vulnerable › Vulnerabilities

CVE-2017-6030: Schneider Electric Modicon PLCs Predictable Value Range from Previous Values

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2017-06-30 · updated 2026-06-17
• Weakness: CWE-343

Description

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

• Modicon M221, all references, all versions: through 1.1.1.5
• Schneider-Electric Modicon M241 Firmware: through 4.0.3.20
• Schneider-Electric Modicon M251 Firmware: through 4.0.3.20

References

• http://www.securityfocus.com/bid/97254
• https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2017/icsa-17-089-02.json
• https://ics-cert.us-cert.gov/advisories/ICSA-17-089-02
• http://www.securityfocus.com/bid/97254
• https://ics-cert.us-cert.gov/advisories/ICSA-17-089-02

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