CVE-2021-29324
📋 TL;DR
CVE-2021-29324 is a stack overflow vulnerability in Moddable v10.5.0's xsScript.c component that allows attackers to execute arbitrary code or cause denial of service. This affects any application or device using the vulnerable Moddable JavaScript engine, particularly IoT devices and embedded systems.
💻 Affected Systems
- Moddable SDK
📦 What is this software?
Moddable by Moddable
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or device takeover
Likely Case
Application crash causing denial of service, potentially disrupting device functionality
If Mitigated
Contained crash with minimal impact if proper sandboxing and memory protections are enabled
🎯 Exploit Status
Proof of concept available in GitHub issue #586; exploitation requires triggering the vulnerable script parsing function
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v10.5.1 and later
Vendor Advisory: https://github.com/Moddable-OpenSource/moddable/issues/586
Restart Required: Yes
Instructions:
1. Update Moddable SDK to v10.5.1 or later. 2. Recompile all applications using the updated SDK. 3. Redeploy/reinstall patched applications. 4. Restart affected devices/services.
🔧 Temporary Workarounds
Input validation and sanitization
allImplement strict input validation for all script inputs to prevent triggering the overflow
Memory protection hardening
linuxEnable stack canaries and ASLR if supported by the platform
gcc -fstack-protector-all -pie -fPIE
🧯 If You Can't Patch
- Network segmentation to isolate vulnerable devices from untrusted networks
- Implement strict input validation and sanitization for all script execution
🔍 How to Verify
Check if Vulnerable:
Check Moddable SDK version: if exactly v10.5.0, you are vulnerableCheck Version:
Check package.json or build configuration for Moddable versionVerify Fix Applied:
Verify Moddable SDK version is v10.5.1 or later and recompile applications📡 Detection & Monitoring
Log Indicators:
- Application crashes with segmentation faults
- Unexpected process termination
- Memory access violation errors
Network Indicators:
- Unusual script execution patterns
- Large script payloads to vulnerable endpoints
SIEM Query:
process.name:"moddable" AND (event.type:"crash" OR event.type:"segfault")