# CVE-2023-4346: KNX Association KNX Protocol Connection Authorization Option 1 Overly Restrictive Account Lockout Mechanism

> Attackers can lock KNX devices by setting a BCU key, preventing user access and requiring physical intervention to reset.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Yes, since 15 Jul 2026 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 29 Aug 2023
- **Updated:** 16 Jul 2026
- **Also known as:** GHSA-qccg-qqvh-pq7q

## What is CVE-2023-4346?

CVE-2023-4346 is a high-severity denial of service vulnerability in KNX Protocol Connection Authorization Option 1, published on 29 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

KNX devices that use KNX Connection Authorization and support Option 1 are, depending on the implementation, vulnerable to being locked and users being unable to reset them to gain access to the device. The BCU key feature on the devices can be used to create a password for the device, but this password can often not be reset without entering the current password. If the device is configured to interface with a network, an attacker with access to that network could interface with the KNX installation, purge all devices without additional security options enabled, and set a BCU key, locking the device. Even if a device is not connected to a network, an attacker with physical access to the device could also exploit this vulnerability in the same way.

Weakness: CWE-645 (Overly Restrictive Account Lockout Mechanism)

## Which versions are affected by CVE-2023-4346?

It affects 1 product.


Products: Knx Connection Authorization.

## How do I fix CVE-2023-4346?

No fix has been published for CVE-2023-4346 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 29 Jul 2026.

## Is CVE-2023-4346 being exploited?

Yes. Attackers have exploited CVE-2023-4346 in the wild since at least 15 Jul 2026.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-4346 and fix it if it is affected.

What it is: CVE-2023-4346 is a high-severity denial of service vulnerability in KNX Protocol Connection Authorization Option 1, published on 29 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2023-4346 in the wild since at least 15 Jul 2026.

Affected product: KNX Protocol Connection Authorization Option 1. 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-2023-4346/ (Markdown: https://insights.sbomify.com/CVE-2023-4346/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-4346
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-4346
- OSV: https://osv.dev/vulnerability/CVE-2023-4346

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-4346/
Summaries are generated and may contain mistakes; the official description above is the record.