ExploitedIn CISA KEV

CVE-2021-22681

Exploitation confirmed. First attested on 2026-03-05 by CISA-ADP, CISA KEV, GCVE · kevintel.

Published2021-03-03
WeaknessCWE-522

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC

2021-03-0318:15CVE publishedNVD
2026-03-05Listed as exploited by GCVEGCVE
2026-03-05Exploitation first reportedCISA KEV
2026-03-05Added to the CISA KEV catalogCISA KEV
2026-03-0519:14SSVC exploitation set to activeCISA-ADP
2026-10-2319:23First public proof of conceptPoC-in-GitHub
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-22681?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-22681?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Rockwellautomation factorytalk services platformversion to verify

Branch	Affected	Fixed in	Source
2.10+	≥ 2.10	no fix published	NVD

Rockwellautomation rslogix 5000version to verify

Branch	Affected	Fixed in	Source
20.x	≥ 16, ≤ 20	no fix published	NVD

Rockwellautomation studio 5000 logix designerversion to verify

Branch	Affected	Fixed in	Source
21.0+	≥ 21.0	no fix published	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

ICSA-21-056-03 CISA3 known affected
Rockwell Automation Logix Controllers (Update A)
RSLogix 5000: Versions 16 through 20 · Studio 5000 Logix Designer: Versions 21 and later · FactoryTalk Security part of the FactoryTalk Services Platform if configured and deployed: v2.10 and later

Full record on NVD

Fix

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.due 2026-03-26
Mitigation from the vendor CISA ICSA-21-056-03 · 3 productsRockwell Automation has determined this vulnerability cannot be mitigated with a patch. Rockwell encourages users to combine its specific risk mitigation recommendations with general security guidelines for a comprehensive defense-in-depth strategy.
Mitigation from the vendor CISA ICSA-21-056-03 · 3 productsA comprehensive defense-in-depth strategy can reduce the risk of this vulnerability. To reduce risk, Rockwell recommends users ensure they are employing proper network segmentation and security controls
Mitigation from the vendor CISA ICSA-21-056-03 · 3 productsMinimizing network exposure for all control system devices and/or systems and confirm these devices are not accessible from the Internet.
Mitigation from the vendor CISA ICSA-21-056-03 · 3 productsLocating control system networks and devices behind firewalls and isolating them from the enterprise/business network.
Mitigation from the vendor CISA ICSA-21-056-03 · 3 productsRestricting or blocking traffic on TCP 44818 from outside of the industrial control system network zone. For more information on the TCP/UDP ports used by Rockwell Automation products, see BF7490 (login required).
Mitigation from the vendor CISA ICSA-21-056-03 · 3 productsWhen remote access is required, use secure methods such as virtual private networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. VPN is only as secure as the connected devices.

Detection

read 2026-10-23 19:23 UTC

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: 1 repository, unverifiedpcrosby-1990/cip-security-poc

CISA Known Exploited Vulnerability

Date Added: 2026-03-05
Patch Due Date: 2026-03-26
Ransomware Use: Unknown
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.

Sources

CISA KEVKEV entry2026-03-05
GCVEexploitation2026-03-05
CISA-ADPSSVC decisionactive2026-03-05
OpenCVESSVC decisionactive—
CISA-ADPCVSS 3.19.82026-03-05
NVDCVSS 3.19.8read 2026-10-23
NVDCVSS 2.07.5read 2026-10-23
CNAweakness (CWE)CWE-522read 2026-10-23
NVDweakness (CWE)CWE-522read 2026-10-23
FIRST EPSSEPSS score63.6 %read 2026-10-23
PoC-in-GitHubproof of concept1read 2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2021-03-03
Last Modified: 2026-06-17
NVD status: Analyzed

Frequently asked questions

What is CVE-2021-22681?

Is CVE-2021-22681 actively exploited?

Yes. CVE-2021-22681 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2026-03-26.

What is the CVSS score for CVE-2021-22681?

CVE-2021-22681 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Hear about the next vulnerability in your software

Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».

Get alerts for this product CISA KEV additions, March 2026 Search CVEs

No credit card required · No monthly cap on website lookups · 250 API requests/month

Go further

For a threat intelligence platform: malware, C2 and ransomware indicators over STIX/TAXII.
Following what attackers exploit right now? The CISA KEV additions of the month, with their patch deadlines.
Running this software? Vulnerability monitoring alerts you to new vulnerabilities in your products.

Related vulnerabilities

Same product first, then the same vendor advisory and the same publication week.

Back to CVE Database