What’s Vulnerable › Vulnerabilities

CVE-2021-22659

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-03-25 · updated 2026-06-17
• Weakness: CWE-120

Description

Rockwell Automation MicroLogix 1400 Version 21.6 and below may allow a remote unauthenticated attacker to send a specially crafted Modbus packet allowing the attacker to retrieve or modify random values in the register. If successfully exploited, this may lead to a buffer overflow resulting in a denial-of-service condition. The FAULT LED will flash RED and communications may be lost. Recovery from denial-of-service condition requires the fault to be cleared by the user.

Affected products

• Rockwell Automation MicroLogix 1400: through 21.6

References

• https://rockwellautomation.custhelp.com/app/answers/answer_view/a_id/1129877/loc/en_US#__highlight
• https://us-cert.cisa.gov/ics/advisories/icsa-21-033-01
• https://rockwellautomation.custhelp.com/app/answers/answer_view/a_id/1129877/loc/en_US#__highlight
• https://us-cert.cisa.gov/ics/advisories/icsa-21-033-01

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