# CVE-2026-12659: Rockwell Automation Flex 5000® Adapter - Denial of Service

> Attackers can cause a denial of service in Rockwell FLEX 5000 adapters by sending crafted CIP packets, requiring a power cycle to recover.

- **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-vxg7-9hgq-fphj

## What is CVE-2026-12659?

CVE-2026-12659 is a high-severity denial of service vulnerability in Rockwell Automation The FLEX 5000® EtherNet/IP Adapter, 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 in the affected products. The security issue stems from improper handling of exceptional conditions when processing crafted CIP packets sent to the adapter. A power cycle is required to recover the module and associated I/O.

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2026-12659?


## How do I fix CVE-2026-12659?

No fix has been published for CVE-2026-12659 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-12659 being exploited?

There is no known exploitation of CVE-2026-12659 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-12659 and fix it if it is affected.

What it is: CVE-2026-12659 is a high-severity denial of service vulnerability in Rockwell Automation The FLEX 5000® EtherNet/IP Adapter, 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-2026-12659 in the wild and no public exploit code.

Affected product: Rockwell Automation The FLEX 5000® EtherNet/IP Adapter. 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-2026-12659/ (Markdown: https://insights.sbomify.com/CVE-2026-12659/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-12659
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-12659
- OSV: https://osv.dev/vulnerability/CVE-2026-12659

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-12659/
Summaries are generated and may contain mistakes; the official description above is the record.