# CVE-2023-4346: KNX Association KNX Protocol account lockout in Connection Authorization Option 1

Source: https://junglewise.ai/threats/cve-2023-4346-knx-association-knx-protocol-account-lockout-in-connection  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-15. Updated: 2026-07-15  
License: CC BY 4.0 with a link back

CVE-2023-4346 · Severity: critical · CVSS 7.5 · Exploited in the wild · Published 2026-07-15

A vulnerability exists in the KNX protocol, a standard used for building automation and industrial control systems. An attacker with network or physical access can permanently lock building control devices by setting a password (BCU key) that cannot be reset by the legitimate owner. This could lead to a total loss of control over building systems like lighting, HVAC, and security, potentially requiring the physical replacement of hardware to restore operations.

## Quick answers

**Is CVE-2023-4346 exploited in the wild?** Yes. CVE-2023-4346 is known to be exploited in the wild, first recorded on 15 July 2026. Treat it as urgent.

**How severe is CVE-2023-4346?** Critical severity, with a CVSS score of 7.5, published 15 July 2026.

**Which products and versions are affected?** Knx Association KNX Protocol All versions supporting Option 1 without additional security options.

**Is there a fix for CVE-2023-4346?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2023-4346 attacked?** It is attacked over the network or with physical access, in an operating system.

**Am I affected by CVE-2023-4346?** Check whether you run Knx Association KNX Protocol or Knx Association Knx Protocol Connection Authorization Option 1 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is classified as an Overly Restrictive Account Lockout Mechanism (CWE-645) within the KNX Connection Authorization Option 1 implementation. The root cause is the design of the Bus Coupling Unit (BCU) key feature, which allows a password to be set that cannot be reset without the current password. An attacker with network access to the KNX installation can purge all devices that lack additional security options and set a new BCU key. This effectively bricks the device for the legitimate user, as there is no mechanism to override or reset the key once it has been maliciously set. The attack can be performed remotely over a network or via direct physical access to the bus.

## Affected products

- KNX Association KNX Protocol Connection Authorization Option 1 All versions supporting Option 1 without additional security options

## Timeline

- 2023-08-29: advisory: Initial NVD publication
- 2026-07-15: disclosed: Updated advisory information published