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Known exploited vulnerability

CVE-2021-22681

criticalCVSS 3.1 9.8In CISA KEVEPSS 64%Published · n/a

The short answer

CVE-2021-22681 affects n/a Rockwell Automation Studio 5000 Logix Designer, RSLogix 5000, Logix Controllers and is rated critical (CVSS 9.8). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-03-05: attackers are using it, so patch it first.

What it is

Rockwell Automation Studio 5000 Logix Designer Versions 21 and later, and RSLogix 5000 Versions 16 through 20 use a key to verify Logix controllers are communicating with Rockwell Automation CompactLogix 1768, 1769, 5370, 5380, 5480: ControlLogix 5550, 5560, 5570, 5580; DriveLogix 5560, 5730, 1794-L34; Compact GuardLogix 5370, 5380; GuardLogix 5570, 5580; SoftLogix 5800. Rockwell Automation Studio 5000 Logix Designer Versions 21 and later and RSLogix 5000: Versions 16 through 20 are vulnerable because an unauthenticated attacker could bypass this verification mechanism and authenticate with Rockwell Automation CompactLogix 1768, 1769, 5370, 5380, 5480: ControlLogix 5550, 5560, 5570, 5580; DriveLogix 5560, 5730, 1794-L34; Compact GuardLogix 5370, 5380; GuardLogix 5570, 5580; SoftLogix 5800.

Weakness: CWE-522.

Severity

9.8 critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploited (CISA KEV)

Yes, since Mar 5, 2026

Federal due date Mar 26, 2026

EPSS, next 30 days

64%

Higher than 99% of scored CVEs

How it can be exploited

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

What CISA says to do

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Affected products

Rockwell Automation Studio 5000 Logix Designer, RSLogix 5000, Logix Controllers. NVD's record lists the exact affected versions.

References

Questions

Is CVE-2021-22681 being exploited?

Yes. CISA added CVE-2021-22681 to its Known Exploited Vulnerabilities catalog on 2026-03-05, with a federal remediation due date of 2026-03-26.

How do I fix CVE-2021-22681?

CISA's required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.

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