CVE-2025-65502
📋 TL;DR
A null pointer dereference vulnerability in Cesanta Mongoose's add_ca_certs() function allows remote attackers to cause denial of service by triggering TLS initialization when SSL_CTX_get_cert_store() returns NULL. This affects all applications using vulnerable Mongoose versions for TLS connections. The vulnerability is triggered during TLS handshake initialization.
💻 Affected Systems
- Cesanta Mongoose Embedded Web Server
📦 What is this software?
Mongoose by Cesanta
⚠️ Risk & Real-World Impact
Worst Case
Complete service crash and denial of service for all TLS-enabled endpoints, potentially disrupting critical services.
Likely Case
Service crashes when processing malformed TLS connections, causing temporary unavailability until service restarts.
If Mitigated
Service remains available with proper input validation and error handling in place.
🎯 Exploit Status
Exploitation requires sending TLS initialization requests that trigger the null pointer condition. No authentication needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 7.2 and later
Vendor Advisory: https://github.com/cesanta/mongoose/issues/3306
Restart Required: Yes
Instructions:
1. Update Mongoose to version 7.2 or later. 2. Recompile your application with the updated library. 3. Restart the application/service.
🔧 Temporary Workarounds
Disable TLS/SSL
allTemporarily disable TLS functionality if not required for the application.
Configure application to use HTTP instead of HTTPS
Input validation wrapper
allImplement wrapper functions to validate SSL_CTX_get_cert_store() return values before calling add_ca_certs().
🧯 If You Can't Patch
- Implement network-level controls to restrict TLS connections to trusted sources only.
- Deploy monitoring and automatic restart mechanisms to detect and recover from crashes.
🔍 How to Verify
Check if Vulnerable:
Check Mongoose version in your application. If version < 7.2 and TLS is enabled, the system is vulnerable.Check Version:
Check application documentation or build configuration for Mongoose version. For source builds: grep -r "MG_VERSION" in source code.Verify Fix Applied:
Verify Mongoose version is 7.2 or later and test TLS connections to ensure no crashes occur.📡 Detection & Monitoring
Log Indicators:
- Application crash logs mentioning Mongoose
- Segmentation fault errors during TLS handshake
- Unexpected service restarts
Network Indicators:
- Multiple failed TLS handshake attempts from single sources
- Abnormal TLS connection patterns
SIEM Query:
source="application.logs" AND ("segmentation fault" OR "crash" OR "null pointer") AND "mongoose"