CVE-2025-65503
📋 TL;DR
A use-after-free vulnerability in Redboltz async_mqtt 10.2.5 allows local users to cause denial of service by triggering SSL initialization failures, leading to incorrect destruction order between io_context and endpoint objects. This affects systems running the vulnerable async_mqtt library version. The vulnerability requires local access to exploit.
💻 Affected Systems
- Redboltz async_mqtt
📦 What is this software?
Async Mqtt by Redboltz
⚠️ Risk & Real-World Impact
Worst Case
Complete service crash and denial of service for MQTT functionality, potentially disrupting dependent applications.
Likely Case
Local denial of service affecting MQTT operations when SSL initialization fails under specific conditions.
If Mitigated
Minimal impact with proper access controls preventing local exploitation.
🎯 Exploit Status
Requires local access and ability to trigger SSL initialization failures.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in versions after 10.2.5
Vendor Advisory: https://github.com/redboltz/async_mqtt/pull/437
Restart Required: Yes
Instructions:
1. Update async_mqtt to latest version. 2. Rebuild applications using the library. 3. Restart affected services.
🔧 Temporary Workarounds
Restrict local access
allLimit local user access to systems running vulnerable async_mqtt
SSL configuration hardening
allEnsure SSL/TLS configuration is properly set up to prevent initialization failures
🧯 If You Can't Patch
- Implement strict access controls to prevent local users from triggering SSL failures
- Monitor for service crashes and implement automatic restart mechanisms
🔍 How to Verify
Check if Vulnerable:
Check async_mqtt version: grep -r 'async_mqtt' in build files or check package managerCheck Version:
Check build configuration or package manager for async_mqtt versionVerify Fix Applied:
Verify async_mqtt version is newer than 10.2.5 and check for presence of fix from PR #437📡 Detection & Monitoring
Log Indicators:
- Unexpected service crashes
- SSL initialization failure messages
- Use-after-free error messages
Network Indicators:
- MQTT service unavailability
- Connection failures to MQTT broker
SIEM Query:
Search for 'async_mqtt crash' OR 'SSL initialization failed' in application logs