CVE-2023-4346

HIGH

7.5

CVSS Score

Published: August 29, 2023 at 07:38 PM UTC

Updated: July 16, 2026 at 05:16 AM UTC

2 products affected across 2 vendorsConnection AuthorizationConnection Authorization

Using KNX Protocol Connection Authorization Option 1 by KNX Association?

Get instant alerts when new vulnerabilities affect KNX Protocol Connection Authorization Option 1 - before attackers find them.

Real-time alertsTrack your software stackFree plan available

Start Free Sign In

Severity

HIGH7.5

Exploitation

CISA KEV

Exploit prediction

EPSS 1%

SSVC

Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score1.4%

EPSS (Exploit Prediction Scoring System) estimates a 1.4% chance this CVE is exploited in the wild within the next 30 days — higher than 72% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

KNX Association KNX Protocol Connection Authorization Option 1 contains an overly restrictive account lockout mechanism vulnerability that could allow an attacker to purge all devices without additional security options enabled and set a BCU key to lock the device.

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.

Ransomware Use

Unknown

Added to KEV

Jul 15, 2026

Remediation Due

Jul 29, 2026

92 days overdue

Notes

https://www.cisa.gov/news-events/ics-advisories/icsa-23-236-01

BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk

Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk

https://nvd.nist.gov/vuln/detail/CVE-2023-4346

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.