CVE-2025-51381
📋 TL;DR
An authentication bypass vulnerability in KCM3100 firmware allows attackers on the same local network to gain unauthorized access without valid credentials. This affects all KCM3100 devices running version 1.4.2 or earlier. Attackers can potentially take full control of affected devices.
💻 Affected Systems
- KCM3100
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attacker to reconfigure settings, intercept traffic, or use device as pivot point for further network attacks.
Likely Case
Unauthorized access to device administration interface leading to configuration changes, service disruption, or credential harvesting.
If Mitigated
Limited impact if device is isolated in separate VLAN with strict network segmentation and access controls.
🎯 Exploit Status
Exploitation requires LAN access but no authentication. Attack vectors likely involve crafted HTTP requests or API calls.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Ver1.4.3 or later
Vendor Advisory: https://notices.jcom.co.jp/notice/93847.html
Restart Required: Yes
Instructions:
1. Download firmware update from vendor site. 2. Log into device admin interface. 3. Navigate to firmware update section. 4. Upload and apply new firmware. 5. Reboot device.
🔧 Temporary Workarounds
Network Segmentation
allIsolate KCM3100 devices in separate VLAN with strict firewall rules
Access Control Lists
allImplement network ACLs to restrict access to KCM3100 management interfaces
🧯 If You Can't Patch
- Physically isolate device on dedicated network segment
- Implement strict firewall rules blocking all unnecessary traffic to device
🔍 How to Verify
Check if Vulnerable:
Check firmware version in device web interface or via SSH if enabled. Version 1.4.2 or earlier indicates vulnerability.Check Version:
Check web interface at http://[device-ip]/status or via SSH: show versionVerify Fix Applied:
Confirm firmware version is 1.4.3 or later in device administration interface.📡 Detection & Monitoring
Log Indicators:
- Unauthorized access attempts to admin interface
- Multiple failed login attempts followed by successful access without valid credentials
- Configuration changes from unexpected IP addresses
Network Indicators:
- Unusual HTTP requests to device management ports
- Traffic patterns indicating authentication bypass attempts
- Unexpected administrative access from non-authorized hosts
SIEM Query:
source_ip IN (internal_range) AND dest_port=80 AND (uri CONTAINS "/admin" OR uri CONTAINS "/config") AND response_code=200 AND NOT user_agent IN (approved_agents)