CVE-2023-4346: KNX Association KNX Protocol Connection Authorization Option 1 Overly Restrictive Account Lockout Mechanism Vulnerability
What it is
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.
What to do
Schedule the vendor fix into this week’s change window, prioritising internet-facing and business-critical systems. Confirm the fix is applied everywhere, not just where it was easy.
- Priority
- This week: Schedule into this week’s change window.
- Severity (CVSS)
- 7.5 high
- CISA assessment (SSVC)
- actively exploited; attackers can automate it at scale; partial control or data exposure
- Exploit probability (EPSS, 30 days)
- 1.3%, higher than 69% of all CVEs
- Added to CISA KEV
- 15 July 2026
- CISA fix-by date
- 29 July 2026 (US federal agencies; a sensible deadline for everyone)
- Ransomware use
- Not known
- Weakness
- CWE-645
References
- NIST NVD entry
- CISA KEV entry
- www.cisa.gov/news-events/ics-advisories/icsa-23-236-01
- www.cisa.gov/news-events/ics-advisories/icsa-23-236-01
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-4346
Sources: CISA Known Exploited Vulnerabilities · FIRST Exploit Prediction Scoring System (EPSS) · NIST National Vulnerability Database · CISA Vulnrichment (SSVC), via the CVE Program. This product uses data from the NVD API but is not endorsed or certified by the NVD. Summaries are machine-written from CISA’s description; treat the vendor’s advisory as the authority for fixes.