Vulnerability report

Exploitation attempts observed in the wild Confirmed confidence In CISA KEV

CVE-2021-22681

Studio 5000 Logix Designer

Rockwell Automation / Studio 5000 Logix Designer · RSLogix 5000 Versions 16 through 20

Watch CVE-2021-22681 Browse KEV feed
Severity
CVSS 9.8 · Critical
Confidence
Confirmed
Exploit status
Exploitation attempts observed in the wild
EPSS
63.6%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2021-22681 is an unauthenticated vulnerability affecting Rockwell Automation Studio 5000 Logix Designer, RSLogix 5000. Rockwell Automation Studio 5000 Logix Designer Versions 21 and later, and RSLogix 5000...

Have exploitation attempts been observed?

Yes. Exploitation attempts have been reported for this vulnerability. Previdian lists it as a known exploited vulnerability. Listed in CISA KEV. Also reported by third-party sources. Confidence is confirmed.

Who is affected?

Rockwell Automation / Studio 5000 Logix Designer rslogix 5000 versions 16 through 20.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Studio 5000 Logix Designer

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.

n/a Affected
Rockwell Automation Studio 5000 Logix Designer, RSLogix 5000, Logix Controllers
RSLogix 5000 Versions 16 through 20 Studio 5000 Logix Designer: Versions 21 and later 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
Published
03 Mar 2021
Exploitation Attempts Reported
01 Jun 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

cisa

CVE References

Exploitation evidence

Evidence of exploitation attempts

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploitation attempts observed in the wild

CVE

Recorded 01 Jun 2026

A trusted third party reported exploitation attempts.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
CVE First 2026-06-01 11:38 UTC
CISA 2026-06-02 14:02 UTC
Tenable Blog 2026-07-29 03:19 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

9.8 Critical

Potential damage if exploited. Separate from whether attackers are using it.

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

EPSS

63.6%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Insufficiently Protected Credentials CWE-522

Recent mention · Tenable Blog

Coordinated “cyberattack” on Minnesota water utilities: What you need to know

A coordinated cyber attack disrupted water systems across more than 30 Minnesota communities. Here is what defenders need to know about the attack so far. This FAQ also details recent cyberactivity targeting internet-exposed PLCs, and how to protect exposed infrastructure.Key...

Read full advisory

All CVSS Scores

CVSS v3.1 9.8 Critical

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

CVSS v2.0 7.5 High

AV:N/AC:L/Au:N/C:P/I:P/A:P

Timeline

From disclosure to observed exploitation attempts

  1. 03:19 UTC

    KEV confirmed by Tenable Blog

    Exploitation attempts reported by an external source

  2. 14:02 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  3. 11:38 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party report of exploitation attempts

  4. 17:59 UTC

    CVE published

    Vulnerability disclosed publicly

  5. 00:00 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

Start 14-day Pro trial Read API docs
  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2021-22681

Sample API response 
{
  "cve_id": "CVE-2021-22681",
  "confidence": "Confirmed",
  "cvss_score": 9.8,
  "cvss_estimated": false,
  "epss_score": 0.6363,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}