CVE-2024-50921
📋 TL;DR
Insecure permissions in Silicon Labs Z-Wave Series 700 and 800 controllers allow attackers to cause denial of service by repeatedly sending crafted packets. This affects Z-Wave smart home and IoT devices using vulnerable controller firmware. The vulnerability enables disruption of Z-Wave network communications.
💻 Affected Systems
- Silicon Labs Z-Wave Series 700 controllers
- Silicon Labs Z-Wave Series 800 controllers
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete disruption of Z-Wave network communications, rendering all connected smart devices (lights, locks, sensors) unresponsive until controller restart.
Likely Case
Intermittent Z-Wave network instability causing device disconnections and delayed responses in smart home/IoT environments.
If Mitigated
Minimal impact with proper network segmentation and packet filtering preventing crafted packets from reaching controllers.
🎯 Exploit Status
Exploitation requires sending crafted Z-Wave packets to the controller, which can be done from devices on the same network segment.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v7.21.2 or later
Vendor Advisory: https://www.silabs.com/security
Restart Required: Yes
Instructions:
1. Check current firmware version on Z-Wave controller. 2. Download updated firmware from Silicon Labs support portal. 3. Apply firmware update following manufacturer instructions. 4. Restart controller to activate new firmware.
🔧 Temporary Workarounds
Network Segmentation
allIsolate Z-Wave controllers on separate VLAN to prevent unauthorized network access
Packet Filtering
linuxConfigure firewall rules to restrict Z-Wave traffic to trusted sources only
iptables -A INPUT -p udp --dport 41230 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p udp --dport 41230 -j DROP
🧯 If You Can't Patch
- Segment Z-Wave network from general network traffic using VLANs or physical separation
- Implement strict firewall rules to only allow Z-Wave traffic from authorized devices
🔍 How to Verify
Check if Vulnerable:
Check controller firmware version via manufacturer's management interface or CLI. Vulnerable if version is exactly v7.21.1.Check Version:
Manufacturer-specific command via controller CLI or web interface (varies by device)Verify Fix Applied:
Confirm firmware version is v7.21.2 or later and test Z-Wave network stability under normal traffic.📡 Detection & Monitoring
Log Indicators:
- Unusual Z-Wave packet rejection logs
- Controller restart events
- High frequency of malformed packet warnings
Network Indicators:
- Abnormally high Z-Wave traffic (41230/UDP) from single source
- Repeated identical Z-Wave packets
SIEM Query:
source_port:41230 AND packet_count > 1000 AND time_window:1m