# CVE-2026-9653: 1756-EN2, 1756-EN3, and 1756-ENBT - Denial of Service via CIP Connection ID

> An attacker can cause temporary denial of service on Rockwell industrial communication modules by sending crafted CIP packets.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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-w8xr-7458-qr4m

## What is CVE-2026-9653?

CVE-2026-9653 is a high-severity denial of service vulnerability in Rockwell Automation 1756-EN2, 1756-EN3, 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 denial-of-service security issue exists across all the 1756-EN2, EN3, and ENBT communication module due to improper validation of CIP Implicit Connection packets. An attacker on the network can exploit this by sending crafted packets to continuously disrupt device connections, though device connections will recover immediately after.

Weakness: CWE-354 (Improper Validation of Integrity Check Value)

## Which versions are affected by CVE-2026-9653?


## How do I fix CVE-2026-9653?

No fix has been published for CVE-2026-9653 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-9653 being exploited?

There is no known exploitation of CVE-2026-9653 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-9653 and fix it if it is affected.

What it is: CVE-2026-9653 is a high-severity denial of service vulnerability in Rockwell Automation 1756-EN2, 1756-EN3, 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-2026-9653 in the wild and no public exploit code.

Affected product: Rockwell Automation 1756-EN2, 1756-EN3. 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-2026-9653/ (Markdown: https://insights.sbomify.com/CVE-2026-9653/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-9653
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-9653
- OSV: https://osv.dev/vulnerability/CVE-2026-9653

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-9653/
Summaries are generated and may contain mistakes; the official description above is the record.