CVE-2021-41751
📋 TL;DR
This is a critical buffer overflow vulnerability in JerryScript's array slice function that allows remote code execution. It affects systems running vulnerable versions of JerryScript, a lightweight JavaScript engine commonly embedded in IoT devices and resource-constrained environments. Attackers can exploit this to execute arbitrary code with the privileges of the JerryScript process.
💻 Affected Systems
- JerryScript JavaScript engine
📦 What is this software?
Jerryscript by Jerryscript
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via remote code execution leading to data theft, ransomware deployment, or botnet recruitment.
Likely Case
Remote code execution allowing attackers to take control of affected devices, potentially pivoting to other systems.
If Mitigated
Limited impact if proper network segmentation and least privilege principles are applied, though exploitation risk remains.
🎯 Exploit Status
Buffer overflow in array slice function requires minimal attacker skill to exploit. Public PoC exists in the GitHub pull request.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Commit e1ce7dd7271288be8c0c8136eea9107df73a8ce2 and later
Vendor Advisory: https://github.com/jerryscript-project/jerryscript/pull/4797
Restart Required: Yes
Instructions:
1. Update JerryScript to commit e1ce7dd7271288be8c0c8136eea9107df73a8ce2 or later. 2. Rebuild any applications using JerryScript. 3. Restart affected services/devices.
🔧 Temporary Workarounds
Disable array slice functionality
allRemove or disable usage of Array.prototype.slice() in JavaScript code running on JerryScript
Modify JavaScript code to avoid slice() calls
Implement custom slice function with bounds checking
🧯 If You Can't Patch
- Network segmentation: Isolate JerryScript devices from untrusted networks
- Implement strict input validation and sanitization for all JavaScript inputs
🔍 How to Verify
Check if Vulnerable:
Check JerryScript version/git commit hash. If before e1ce7dd7271288be8c0c8136eea9107df73a8ce2, vulnerable.Check Version:
git log --oneline -1 (if built from source) or check application version informationVerify Fix Applied:
Verify JerryScript is at commit e1ce7dd7271288be8c0c8136eea9107df73a8ce2 or later. Test array slice operations with edge cases.📡 Detection & Monitoring
Log Indicators:
- Process crashes of JerryScript applications
- Unusual memory access patterns
- Multiple failed array operations
Network Indicators:
- Unexpected network connections from JerryScript devices
- Suspicious JavaScript payloads containing array slice operations
SIEM Query:
Process:jerryscript AND (EventID:1000 OR "access violation" OR "segmentation fault")