Affects widely deployed Rockwell Automation PLC families (CompactLogix/ControlLogix/EN4). Bypass of CIP Security can disrupt industrial operations across multiple sectors.
CVE-2026-9636
Controllers accept certificates signed by revoked intermediate, enabling CIP Security bypass.
Is CVE-2026-9636 being exploited?
Not confirmed. CVE-2026-9636 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.22% probability of exploitation in the next 30 days.
How severe is CVE-2026-9636?
CVE-2026-9636 is rated High with a CVSS score of 8.2. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-9636?
Yes. A fix has been recorded for CVE-2026-9636. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-9636 affect?
CVE-2026-9636 affects Rockwell CompactLogix 5380, Rockwell ControlLogix 5580, EN4 communication modules. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-9636?
Restrict control network access, enforce CRL/OCSP, apply vendor patch when released.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Network attacker can present a cert signed by a revoked intermediate to authenticate, bypass CIP Security and access/control PLCs or automation networks.
Immediate action required
- affectedVersion 36 - Version 37
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.