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

July 30, 2026·Source: CISA

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TL;DR

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issue stems from the controller failing to properly reject certificates signed by an intermediate certificate that has been revoked via a Certificate Revocation List (CRL).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 fix Rockwell Automation recommend users update to the following versi

What Happened

Rockwell Automation CompactLogix 5380 ControlLogix 5580 / 1756-EN4TR Communications Module, reported by CISA.

v3 5.9 Rockwell Automation Rockwell Automation CompactLogix 5380 ControlLogix 5580 / 1756-EN4TR Communications Module Improper Check for Certificate Revocation

For the full technical details, see the original report.

Why It Matters for Businesses

This development could affect organizations that rely on the impacted technologies or services. Unpatched systems, misconfigured infrastructure, or lack of monitoring can leave businesses exposed to exploitation, data breaches, and regulatory penalties.

How to Check Your Exposure

Run a free scan on NEL Professional's Cyber Risk Scanner to check whether your domain is affected. The scan covers SSL/TLS, security headers, DNS configuration, email authentication, and more across 16 modules.

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Mitigation Steps

Patch immediately, Apply vendor patches or updates as soon as they are available.
Review configurations, Check firewall rules, access controls, and security headers.
Monitor logs, Watch for indicators of compromise (IOCs) related to this threat.
Update security policies, Ensure incident response plans cover this type of threat.
Run a security scan, Use automated tools to verify your exposure.

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