Actively exploited · Published Aug 29, 2023 · Assigned by icscert
CVE-2023-4346
High 7.5 Exploited
In plain English
A high-severity security flaw in KNX Protocol Connection Authorization Option 1 from KNX Association. Attackers are actively exploiting it in the wild (listed by CISA on July 15, 2026). The chance it is exploited in the next 30 days is estimated at 1.4% (higher than 72% of all known vulnerabilities). 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.
CISA guidance
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.
Federal agencies must remediate by Jul 29, 2026.
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| KNX Association | KNX Protocol Connection Authorization Option 1 | 0 |
Weakness: CWE-645 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://www.cisa.gov/news-events/ics-advisories/icsa-23-236-01 government-resource
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-4346 government-resource