CVE-2025-12790
📋 TL;DR
CVE-2025-12790 is a vulnerability in Rubygem MQTT where default configurations lack hostname validation, enabling Man-in-the-Middle attacks. This allows attackers to intercept and potentially modify MQTT communications between clients and brokers. Any Ruby application using vulnerable versions of the ruby-mqtt gem with default settings is affected.
💻 Affected Systems
- ruby-mqtt gem
⚠️ 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
Attackers could intercept sensitive MQTT data (credentials, IoT commands, sensor data), inject malicious payloads, or impersonate legitimate MQTT brokers to control connected devices.
Likely Case
Interception of unencrypted or weakly authenticated MQTT traffic in environments where attackers can position themselves between clients and brokers.
If Mitigated
Minimal impact if TLS with proper certificate validation is already configured or if network segmentation prevents MITM positioning.
🎯 Exploit Status
Exploitation requires network access to perform MITM attacks. No authentication needed beyond network positioning.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.7.0 and later
Vendor Advisory: https://github.com/njh/ruby-mqtt/blob/main/NEWS.md#ruby-mqtt-version-070-2025-10-29
Restart Required: Yes
Instructions:
1. Update Gemfile to specify 'gem "mqtt", ">= 0.7.0"'. 2. Run 'bundle update mqtt'. 3. Restart all Ruby applications using the mqtt gem.
🔧 Temporary Workarounds
Enable hostname validation manually
allConfigure MQTT client with explicit hostname validation before patching
MQTT::Client.connect(host: 'broker.example.com', ssl: {verify_mode: OpenSSL::SSL::VERIFY_PEER, verify_hostname: true})
🧯 If You Can't Patch
- Use network segmentation to isolate MQTT traffic and prevent MITM positioning
- Implement certificate pinning or use VPN tunnels for all MQTT communications
🔍 How to Verify
Check if Vulnerable:
Check Gemfile.lock or run 'bundle show mqtt' to see installed version. Versions below 0.7.0 are vulnerable.Check Version:
ruby -e "require 'mqtt'; puts MQTT::VERSION" or bundle show mqttVerify Fix Applied:
Confirm version 0.7.0 or higher is installed and verify SSL context includes verify_hostname: true in connection code.📡 Detection & Monitoring
Log Indicators:
- Unexpected certificate validation errors
- Connection attempts from unexpected IPs to MQTT brokers
Network Indicators:
- Unusual TLS handshake patterns
- MQTT traffic interception attempts
SIEM Query:
source="mqtt.log" AND ("certificate" AND "validation") OR ("SSL" AND "error")