CVE-2020-25464
📋 TL;DR
This heap buffer overflow vulnerability in the Moddable SDK's debug component allows attackers to crash applications or potentially execute arbitrary code by exploiting stack overflow during debug frame creation. It affects applications built with vulnerable versions of the Moddable SDK, particularly those with debug functionality enabled.
💻 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 if debugger functionality is exposed to attackers.
Likely Case
Application crash (denial of service) when debugger attempts to handle malformed stack frames.
If Mitigated
No impact if debug functionality is disabled or proper input validation is implemented.
🎯 Exploit Status
Exploitation requires triggering specific stack overflow conditions during debug frame creation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 20200903 or later
Vendor Advisory: https://github.com/Moddable-OpenSource/moddable/issues/431
Restart Required: Yes
Instructions:
1. Update Moddable SDK to version 20200903 or later. 2. Rebuild all applications with the updated SDK. 3. Redeploy updated applications to affected systems.
🔧 Temporary Workarounds
Disable Debug Functionality
allDisable debugger support in production builds to eliminate the vulnerable code path.
Build with debug disabled: xsbug = false in manifest.json
🧯 If You Can't Patch
- Disable all debug functionality in production environments
- Implement network segmentation to isolate systems with debug capabilities
🔍 How to Verify
Check if Vulnerable:
Check Moddable SDK version: grep -r 'MODDABLE' in SDK directory or check package.json versionCheck Version:
Check xs.h or package.json for version informationVerify Fix Applied:
Verify SDK version is 20200903 or later and rebuild applications with updated SDK📡 Detection & Monitoring
Log Indicators:
- Application crashes with stack overflow errors
- Debugger connection failures
Network Indicators:
- Unexpected connections to debug ports (typically 8080)
SIEM Query:
Application logs containing 'xsDebug.c' or 'stack overflow' errors