CVE-2026-9636: CWE-299 Improper check for certificate revocation in Rockwell Automation ControlLogix® 5580, CompactLogix® 5380, GuardLogix® 5580, Compact GuardLogix® 5380, 1756-EN4TR
A security issue exists within CompactLogix® 5380, ControlLogix® 5580, and EN4 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issue stems from the controller failing to properly reject certificates signed by an intermediate certificate that has been revoked via a Certificate Revocation List (CRL).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.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-9636) involves improper certificate revocation checking (CWE-299) in Rockwell Automation's ControlLogix® 5580, CompactLogix® 5380, GuardLogix® 5580, Compact GuardLogix® 5380, and 1756-EN4TR modules. Specifically, the controllers fail to properly reject certificates signed by an intermediate certificate that has been revoked via a CRL. This improper validation could allow an attacker on the network to use a revoked intermediate certificate to establish a connection that should be denied by CIP Security mechanisms. The vulnerability is rated high severity with a CVSS 4.0 score of 8.2. No vendor advisory or patch information is currently available, and no exploits are known in the wild.
Potential Impact
An attacker could potentially bypass CIP Security protections by using a revoked intermediate certificate to establish a connection with affected controllers. This undermines the trust model of certificate-based authentication and could lead to unauthorized access or control over the affected industrial control system components. The impact is limited to the ability to establish unauthorized connections due to improper certificate revocation checking.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, organizations should monitor Rockwell Automation advisories for updates. Network-level controls restricting access to affected devices and enhanced monitoring for anomalous connections may help reduce risk, but no specific vendor-recommended mitigations are currently documented.
CVE-2026-9636: CWE-299 Improper check for certificate revocation in Rockwell Automation ControlLogix® 5580, CompactLogix® 5380, GuardLogix® 5580, Compact GuardLogix® 5380, 1756-EN4TR
Description
A security issue exists within CompactLogix® 5380, ControlLogix® 5580, and EN4 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.
CVSS v4.0
Score 8.2high
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-9636) involves improper certificate revocation checking (CWE-299) in Rockwell Automation's ControlLogix® 5580, CompactLogix® 5380, GuardLogix® 5580, Compact GuardLogix® 5380, and 1756-EN4TR modules. Specifically, the controllers fail to properly reject certificates signed by an intermediate certificate that has been revoked via a CRL. This improper validation could allow an attacker on the network to use a revoked intermediate certificate to establish a connection that should be denied by CIP Security mechanisms. The vulnerability is rated high severity with a CVSS 4.0 score of 8.2. No vendor advisory or patch information is currently available, and no exploits are known in the wild.
Potential Impact
An attacker could potentially bypass CIP Security protections by using a revoked intermediate certificate to establish a connection with affected controllers. This undermines the trust model of certificate-based authentication and could lead to unauthorized access or control over the affected industrial control system components. The impact is limited to the ability to establish unauthorized connections due to improper certificate revocation checking.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, organizations should monitor Rockwell Automation advisories for updates. Network-level controls restricting access to affected devices and enhanced monitoring for anomalous connections may help reduce risk, but no specific vendor-recommended mitigations are currently documented.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Rockwell
- Date Reserved
- 2026-05-26T18:10:55.329Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a565a3f68715ace43c7b7de
Added to database: 07/14/2026, 15:48:15 UTC
Last enriched: 07/14/2026, 16:03:22 UTC
Last updated: 08/28/2026, 10:52:10 UTC
Views: 108
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