CVE-2026-9636 Security feature bypass in ControlLogix® 5580, CompactLogix® 5380, GuardLogix® 5580, Compact GuardLogix® 5380, 1756-EN4TR
Attackers can bypass CIP Security protections by using certificates signed by revoked intermediate CAs, allowing unauthorized connections to Rockwell PLCs.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-9636?
CVE-2026-9636 is a high-severity vulnerability in Rockwell Automation ControlLogix® 5580, CompactLogix® 5380, GuardLogix® 5580, Compact GuardLogix® 5380, 1756-EN4TR, published on 14 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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issue stems from the controller failing to properly reject certificates signed by an intermediate certificate that has been revoked via a Certificate Revocation List (CRL).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.
Weakness: CWE-299
Which versions are affected by CVE-2026-9636?
How do I fix CVE-2026-9636?
No fix has been published for CVE-2026-9636 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-9636 being exploited?
There is no known exploitation of CVE-2026-9636 in the wild and no public exploit code.
Sources
Also known as GHSA-fvq9-7g3p-r5g2.