CVE-2023-4346: KNX Association KNX Protocol Connection Authorization Option 1 Overly Restrictive Account Lockout Mechanism Vulnerability
KNX Association · KNX Protocol Connection Authorization Option 1 · NVD published 2023-08-30 · posted 2026-07-15 · last modified 2026-07-16
What it is
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 |
|---|---|
| CVSS vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (source: [email protected]) |
| CISA due date | 2026-07-29 (for US federal agencies under BOD; a good deadline for everyone) |
| ATT&CK tactics | n/a |
Exploitation evidence
First exploit evidence seen: 2026-07-15 (earliest date across the sources below).
Exploited in the wild
- CISA KEV: listed since 2026-07-15. Source
Sources: CISA KEV.
No ATT&CK techniques could be mapped or inferred for this CVE yet.
How to fix it
CISA required action
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. (source: CISA KEV)
Fixed versions
NVD does not list a fixed version for this CVE. Use the vendor advisory below.
Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.
Vendor advisories and patches
- https://www.cisa.gov/news-events/ics-advisories/icsa-23-236-01 (CISA KEV notes)
Detection Generic guidance
Response checklist Generic guidance
- Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
- Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
- Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
- Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.