Rockwell Automation CompactLogix 5380 ControlLogix 5580 / 1756-EN4TR Communications Module

Summary

A denial-of-service vulnerability has been identified in Rockwell Automation's CompactLogix 5380, ControlLogix 5580, and 1756-EN4TR Communications Module. Successful exploitation could allow an attacker to disrupt operations. Rockwell Automation has released patches, recommending users update to specific newer versions to mitigate the risk.

Full text

ICS Advisory Rockwell Automation CompactLogix 5380 ControlLogix 5580 / 1756-EN4TR Communications Module Release DateJuly 30, 2026 Alert CodeICSA-26-211-05 Related topics: Industrial Control System Vulnerabilities , Industrial Control Systems View CSAF Summary Successful exploitation of this vulnerability could allow an attacker to cause a denial-of-service condition. The following versions of Rockwell Automation CompactLogix 5380 ControlLogix 5580 / 1756-EN4TR Communications Module are affected: ControlLogix 5580 >=V36|<=V37 (CVE-2026-9636) CompactLogix 5380 >=V36|<=V37 (CVE-2026-9636) GuardLogix 5580 >=V36|<=V37 (CVE-2026-9636) Compact GuardLogix 5380 >=V36|<=V37 (CVE-2026-9636) 1756-EN4TR V6.001 (CVE-2026-9636) 1756-EN4TR V7.001 (CVE-2026-9636) CVSS Vendor Equipment Vulnerabilities v3 5.9 Rockwell Automation Rockwell Automation CompactLogix 5380 ControlLogix 5580 / 1756-EN4TR Communications Module Improper Check for Certificate Revocation Background Critical Infrastructure Sectors: Critical Manufacturing Countries/Areas Deployed: Worldwide Company Headquarters Location: United States Vulnerabilities Expand All + CVE-2026-9636 A security issue exists within CompactLogix 5380, ControlLogix 5580, and EN4TR communication modules related to CIP Security certificate revocation handling. The security issue stems from the controller failing to properly reject certificates signed by an intermediate certificate that has been revoked via a Certificate Revocation List (CRL). This could allow a network-based attacker to establish a connection using a certificate that should be untrusted, potentially bypassing CIP Security protections. View CVE Details Affected Products Rockwell Automation CompactLogix 5380 ControlLogix 5580 / 1756-EN4TR Communications Module Vendor:Rockwell Automation Product Version:Rockwell Automation ControlLogix 5580: >=V36|<=V37, Rockwell Automation CompactLogix 5380: >=V36|<=V37, Rockwell Automation GuardLogix 5580: >=V36|<=V37, Rockwell Automation Compact GuardLogix 5380: >=V36|<=V37, Rockwell Automation 1756-EN4TR: V6.001, Rockwell Automation 1756-EN4TR: V7.001 Product Status:known_affected Remediations Vendor fixRockwell Automation recommend users update to the following versions: ControlLogix 5580: Update to V38.011 Vendor fixCompactLogix 5380: Update to V38.011 Vendor fixGuardLogix 5580: Update to V38.011 Vendor fixCompact GuardLogix 5380: Update to V38.011 Vendor fix1756-EN4TR: Update to V8.001 Relevant CWE: CWE-299 Improper Check for Certificate Revocation Metrics CVSS Version Base Score Base Severity Vector String 3.1 5.9 MEDIUM CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N 4.0 8.2 HIGH CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N Acknowledgments Rockwell Automation reported this vulnerability to CISA Legal Notice and Terms of Use This product is provided subject to this Notification (https://www.cisa.gov/notification) and this Privacy & Use policy (https://www.cisa.gov/privacy-policy). Recommended Practices CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet. Locate control system networks and remote devices behind firewalls and isolating them from business networks. When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as the connected devices. CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures. CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies. CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets. Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies. Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents. CISA also recommends users take the following measures to protect themselves from social engineering attacks: Do not click web links or open attachments in unsolicited email messages. Refer to Recognizing and Avoiding Email Scams for more information on avoiding email scams. Refer to Avoiding Social Engineering and Phishing Attacks for more information on social engineering attacks. No known public exploitation specifically targeting this vulnerability has been reported to CISA at this time. Revision History Initial Release Date: 2026-07-30 Date Revision Summary 2026-07-30 1 Initial Publication Legal Notice and Terms of Use This product is provided subject to this Notification and this Privacy & Use policy. Vendor Rockwell Automation Tags Sector: Critical Manufacturing Sector Topics: Industrial Control System Vulnerabilities, Industrial Control Systems Please share your thoughts We recently updated our anonymous product survey; we welcome your feedback. Related Advisories Jul 30, 2026 ICS Advisory | ICSA-26-211-04 Schneider Electric IGSS Jul 30, 2026 ICS Advisory | ICSA-26-211-02 Johnson Controls OpenBlue Employee Jul 30, 2026 ICS Advisory | ICSA-26-211-01 MikroTik RouterOS Jul 30, 2026 ICS Advisory | ICSA-26-211-03 Toptech Systems RCU II+ and Multiload II+

Entities