CVE-2020-25462
📋 TL;DR
A heap buffer overflow vulnerability in the Moddable SDK's JavaScript engine allows attackers to execute arbitrary code or cause denial of service. This affects applications built with Moddable SDK before version OS200903. The vulnerability is remotely exploitable and can lead to complete system compromise.
💻 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 ransomware deployment.
Likely Case
Application crash and denial of service, potentially leading to system instability.
If Mitigated
Limited impact if proper memory protections and sandboxing are in place, but still significant risk.
🎯 Exploit Status
Exploitation requires crafting malicious JavaScript code to trigger the buffer overflow.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: OS200903
Vendor Advisory: https://github.com/Moddable-OpenSource/moddable/releases/tag/OS200903
Restart Required: Yes
Instructions:
1. Update Moddable SDK to version OS200903 or later. 2. Rebuild all applications with the updated SDK. 3. Redeploy updated applications to affected systems.
🔧 Temporary Workarounds
Disable Arrow Function Support
allTemporarily disable arrow function parsing in JavaScript engine if not required
Modify xsSyntaxical.c to bypass fxCheckArrowFunction
🧯 If You Can't Patch
- Implement strict input validation and sanitization for all JavaScript code
- Deploy applications in sandboxed environments with minimal privileges
🔍 How to Verify
Check if Vulnerable:
Check Moddable SDK version: if version < OS200903, system is vulnerableCheck Version:
Check SDK build configuration or version files in Moddable installationVerify Fix Applied:
Verify SDK version is OS200903 or later and applications have been rebuilt📡 Detection & Monitoring
Log Indicators:
- Application crashes with memory access violations
- Unexpected JavaScript engine termination
Network Indicators:
- Unusual JavaScript payloads in application inputs
SIEM Query:
search 'Moddable SDK crash' OR 'heap buffer overflow' OR 'fxCheckArrowFunction' in application logs