CVE-2021-22681: Rockwell Multiple Products Critical Vulnerability

What is CVE-2021-22681?

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.

Technical Analysis

Weakness Classification

This vulnerability is classified as CWE-522 — Insufficiently Protected Credentials. Credentials are stored or transmitted in a way that allows interception, such as plaintext storage or weak hashing.

Attack Vector Breakdown

• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality: High
• Integrity: High
• Availability: High

Impact Analysis

This vulnerability is exploitable over the network, meaning any system reachable via the internet or internal network is potentially at risk without physical access. The attack complexity is low, requires no special privileges, and needs no user interaction — making it straightforward to exploit at scale. Successful exploitation can result in full confidentiality breach (complete data disclosure), complete integrity compromise (data modification or code execution), total availability loss (denial of service). Credentials are stored or transmitted in a way that allows interception, such as plaintext storage or weak hashing.

Exploitation Probability (EPSS): 18.2% chance of exploitation in the next 30 days (95th percentile). This is a significantly elevated exploitation probability — prioritize patching.

Is CVE-2021-22681 being exploited?

Yes. CVE-2021-22681 is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, restricted to CVEs with confirmed active exploitation in the wild. CISA added this vulnerability on 2026-03-05. Inclusion in KEV triggers the patching mandate under BOD 22-01 for U.S. federal civilian agencies, with a remediation deadline of 2026-03-26.

How to fix CVE-2021-22681

Apply the security update issued by Rockwell for Multiple Products. If an immediate patch is not possible, consult the vendor advisory for mitigation guidance, restrict network exposure of the affected service, and monitor logs for indicators of exploitation. CISA's Known Exploited Vulnerabilities catalog requires U.S. federal agencies to remediate this vulnerability by the due date shown below under Binding Operational Directive 22-01. Private organizations should treat KEV entries as priority-one patches because active exploitation has been confirmed in the wild.

Related Vulnerabilities

Other actively exploited vulnerabilities affecting Multiple Products or sharing the same weakness (CWE-522):

• CVE-2025-43510 (High 7.8) [same product] — A memory corruption issue was addressed with improved lock state checking…
• CVE-2025-43520 (Medium 5.5) [same product] — A memory corruption issue was addressed with improved memory handling. This…
• CVE-2025-31277 (High 8.8) [same product] — The issue was addressed with improved memory handling. This issue is fixed in…
• CVE-2017-7921 (Critical 9.8) [same product] — An Improper Authentication issue was discovered in Hikvision DS-2CD2xx2F-I…
• CVE-2023-43000 (High 8.8) [same product] — A use-after-free issue was addressed with improved memory management. This…

Frequently asked questions

Is CVE-2021-22681 critical?

CVE-2021-22681 has a CVSS 3.1 base score of 9.8 — Critical severity. It should be treated as a priority patch, especially given the active exploitation confirmed by CISA.

Is CVE-2021-22681 being actively exploited?

Yes — CISA added CVE-2021-22681 to the Known Exploited Vulnerabilities catalog on 2026-03-05. Inclusion in KEV means CISA has confirmed in-the-wild exploitation.

How do I patch CVE-2021-22681?

Apply the security update from Rockwell for Multiple Products. Federal agencies must remediate by 2026-03-26 under BOD 22-01.

What type of vulnerability is CVE-2021-22681?

CVE-2021-22681 is classified under CWE-522 (Insufficiently Protected Credentials). Credentials are stored or transmitted in a way that allows interception, such as plaintext storage or weak hashing.

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

CVE-2021-22681 has a CVSS 3.1 base score of 9.8, classifying it as Critical severity. The attack vector is Network, attack complexity is Low, and no privileges are required.