CVE-2021-27425
📋 TL;DR
CVE-2021-27425 is an integer wrap-around vulnerability in Mongoose-OS's mm_malloc function that can lead to arbitrary memory allocation. This could result in system crashes or potentially remote code execution. Organizations using Mongoose-OS v2.17.0 for IoT/embedded devices are affected.
💻 Affected Systems
- Cesanta Mongoose-OS
📦 What is this software?
Mongoose Os by Cesanta
⚠️ Risk & Real-World Impact
Worst Case
Remote attacker gains arbitrary code execution on vulnerable devices, potentially taking full control of IoT/embedded systems.
Likely Case
System instability, crashes, or denial of service affecting device functionality.
If Mitigated
Limited impact with proper memory protections and exploit mitigations in place.
🎯 Exploit Status
Integer overflow vulnerabilities typically require specific memory manipulation knowledge but can be exploited remotely.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v2.18.0 or later
Vendor Advisory: https://github.com/cesanta/mongoose-os
Restart Required: Yes
Instructions:
1. Update Mongoose-OS to version 2.18.0 or later. 2. Rebuild and redeploy firmware to affected devices. 3. Verify the update was successful.
🔧 Temporary Workarounds
Memory allocation limits
allImplement bounds checking for memory allocation requests
// Code modification required - add size validation before mm_malloc calls
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable devices from untrusted networks
- Deploy memory protection mechanisms like ASLR and stack canaries if supported
🔍 How to Verify
Check if Vulnerable:
Check Mongoose-OS version on device: mos --version or examine firmware versionCheck Version:
mos --versionVerify Fix Applied:
Verify version is 2.18.0 or higher and test memory allocation functions📡 Detection & Monitoring
Log Indicators:
- Memory allocation failures
- System crashes
- Unexpected process terminations
Network Indicators:
- Unusual network traffic to IoT devices
- Exploit attempt patterns
SIEM Query:
source="device_logs" AND ("malloc failed" OR "memory error" OR "crash")