AI description
CVE-2023-4346 describes a vulnerability affecting KNX devices that utilize KNX Connection Authorization and support Option 1. The core issue stems from the implementation of the BCU key feature, which allows for the creation of a device password that, in many cases, cannot be reset without knowledge of the existing password. This design flaw can lead to legitimate users being locked out of their devices. An attacker can exploit this vulnerability through either network access, if the device is configured to interface with a network, or physical access to the device. By purging devices that lack additional security options, an attacker can then set their own BCU key, effectively locking out the rightful owners and preventing them from accessing the device. This vulnerability has been added to the CISA's Known Exploited Vulnerabilities Catalog, indicating that it is actively being exploited.
- 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.
- Source
- ics-cert@hq.dhs.gov
- NVD status
- Analyzed
- Products
- connection_authorization
CVSS 3.1
- Type
- Primary
- Base score
- 7.5
- Impact score
- 3.6
- Exploitability score
- 3.9
- Vector string
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Severity
- HIGH
Data from CISA
- Vulnerability name
- KNX Association KNX Protocol Connection Authorization Option 1 Overly Restrictive Account Lockout Mechanism Vulnerability
- Exploit added on
- Jul 15, 2026
- Exploit action due
- Jul 29, 2026
- 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.
- ics-cert@hq.dhs.gov
- CWE-645
- Hype score
- Not currently trending
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