Rockwell Automation CompactLogix 5380 ControlLogix 5580 / 1756-EN4TR Communications Module
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
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issue stems from the controller failing to properly reject certificates signed by an intermediate certificate that has been revoked via a Certificate Revocation List (CRL).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.
Affected Products
Rockwell Automation CompactLogix 5380 ControlLogix 5580 / 1756-EN4TR Communications Module
Rockwell Automation
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
known_affected
Remediations
Vendor fix
Rockwell Automation recommend users update to the following versions: ControlLogix 5580: Update to V38.011
Vendor fix
CompactLogix 5380: Update to V38.011
Vendor fix
GuardLogix 5580: Update to V38.011
Vendor fix
Compact GuardLogix 5380: Update to V38.011
Vendor fix
1756-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