CVE-2021-46328
📋 TL;DR
CVE-2021-46328 is a heap buffer overflow vulnerability in Moddable SDK v11.5.0 that occurs via the __libc_start_main component. This vulnerability could allow attackers to execute arbitrary code or cause denial of service. It affects systems running applications built with the vulnerable Moddable SDK version.
💻 Affected Systems
- Moddable SDK
📦 What is this software?
Moddable Sdk by Moddable
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or persistent backdoor installation.
Likely Case
Application crash causing denial of service, potentially leading to data corruption or service disruption.
If Mitigated
Limited impact with proper memory protection mechanisms (ASLR, DEP) that might only cause crashes.
🎯 Exploit Status
Heap buffer overflows typically require specific memory layout conditions and exploitation techniques like heap spraying.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v11.5.1 and later
Vendor Advisory: https://github.com/Moddable-OpenSource/moddable/issues/751
Restart Required: Yes
Instructions:
1. Update Moddable SDK to version 11.5.1 or later. 2. Rebuild all applications using the updated SDK. 3. Redeploy rebuilt applications to affected systems.
🔧 Temporary Workarounds
Memory Protection Hardening
linuxEnable ASLR and DEP/PaX to make exploitation more difficult
echo 2 > /proc/sys/kernel/randomize_va_space
sysctl -w kernel.exec-shield=1
🧯 If You Can't Patch
- Isolate affected applications in network segments with strict access controls
- Implement application allowlisting to prevent execution of unauthorized code
🔍 How to Verify
Check if Vulnerable:
Check if applications were built with Moddable SDK v11.5.0 by examining build logs or checking SDK version in project configuration.Check Version:
Check xs.h or similar SDK header files for version information, or run 'moddable --version' if available.Verify Fix Applied:
Verify SDK version is 11.5.1 or later and applications have been rebuilt with the updated SDK.📡 Detection & Monitoring
Log Indicators:
- Segmentation fault errors
- Application crashes with memory access violations
- Abnormal process termination
Network Indicators:
- Unexpected network connections from crashed applications
- Traffic patterns suggesting exploitation attempts
SIEM Query:
Process termination events with exit code 139 (SIGSEGV) from Moddable applications