# 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.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Jul 2026
- **Updated:** 14 Jul 2026
- **Also known as:** GHSA-fvq9-7g3p-r5g2

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issue stems from the controller failing to properly reject certificates signed by an intermediate certificate that has been revoked via a Certificate Revocation List (CRL).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

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-9636 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-9636 in the wild and no public exploit code.

Affected product: Rockwell Automation ControlLogix® 5580, CompactLogix® 5380, GuardLogix® 5580, Compact GuardLogix® 5380, 1756-EN4TR. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-9636/ (Markdown: https://insights.sbomify.com/CVE-2026-9636/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-9636
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-9636
- OSV: https://osv.dev/vulnerability/CVE-2026-9636

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-9636/
Summaries are generated and may contain mistakes; the official description above is the record.