How severe is CVE-2026-9636?

CVE-2026-9636 has a CVSS 4.0 base score of 8.2, rated high severity.

Is CVE-2026-9636 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-9636?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-9636 published?

CVE-2026-9636 was published on 2026-07-14.

CVE-2026-9636

CVE-2026-9636 is a high-severity vulnerability with a CVSS 4.0 base score of 8.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-299.

Key facts

Severity: High (CVSS 4.0 base score 8.2)
EPSS exploit prediction: 0% (4th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-299
Published: 2026-07-14
Last modified: 2026-07-14

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issue stems from the controller failing to properly reject certificates signed by an intermediate certificate that has been revoked via a Certificate Revocation List (CRL).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.

Frequently asked questions

What is CVE-2026-9636?: 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issue stems from the controller failing to properly reject certificates signed by an intermediate certificate that has been revoked via a Certificate Revocation List (CRL).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.
How severe is CVE-2026-9636?: CVE-2026-9636 has a CVSS 4.0 base score of 8.2, rated high severity.
Is CVE-2026-9636 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-9636?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-9636 published?: CVE-2026-9636 was published on 2026-07-14.

References

https://www.rockwellautomation.com/en-us/trust-center/security-advisories/advisory.SD1788.html

Other CWE-299 vulnerabilities

CVE-2025-11955 — High (CVSS 8.2): Incorrect validation of OCSP certificates vulnerability in TheGreenBow VPN, versions 7.5 and 7.6. During the IKEv2…
CVE-2025-3085 — High (CVSS 8.1): A MongoDB server under specific conditions running on Linux with TLS and CRL revocation status checking enabled, fails…
CVE-2026-56821 — High (CVSS 7.4): Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final,…
CVE-2026-4428 — High (CVSS 7.4): A logic error in CRL distribution point validation in AWS-LC before 1.71.0 causes partitioned CRLs to be incorrectly…
CVE-2020-16228 — Medium (CVSS 6.4): In Patient Information Center iX (PICiX) Versions C.02 and C.03, PerformanceBridge Focal Point Version A.01,…
CVE-2026-6899 — Medium (CVSS 5.6): Check for certificate revocation only considers the first matching CRL and ignores other valid CRLs of the same CA in…

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