CVE-2021-46482
📋 TL;DR
CVE-2021-46482 is a heap buffer overflow vulnerability in Jsish v3.5.0's NumberConstructor function that allows attackers to execute arbitrary code or cause denial of service. This affects systems running vulnerable versions of Jsish, a JavaScript interpreter for embedded systems. Attackers can exploit this by providing malicious input to trigger the overflow.
💻 Affected Systems
- Jsish
📦 What is this software?
Jsish by Jsish
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or persistent backdoor installation.
Likely Case
Denial of service through application crashes or memory corruption disrupting Jsish-based services.
If Mitigated
Limited impact with proper memory protection mechanisms (ASLR, DEP) making exploitation difficult.
🎯 Exploit Status
Proof of concept exists in GitHub issue #66. Exploitation requires crafting specific input to trigger the overflow.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v3.5.1 and later
Vendor Advisory: https://github.com/pcmacdon/jsish/issues/66
Restart Required: Yes
Instructions:
1. Upgrade Jsish to v3.5.1 or later. 2. Recompile any applications using Jsish. 3. Restart services using Jsish.
🔧 Temporary Workarounds
Input Validation
allImplement strict input validation for data passed to NumberConstructor functions
Memory Protection
linuxEnable ASLR and DEP at OS level to make exploitation more difficult
sysctl -w kernel.randomize_va_space=2
🧯 If You Can't Patch
- Isolate Jsish instances in containers or sandboxes to limit blast radius
- Implement network segmentation to restrict access to systems running vulnerable Jsish
🔍 How to Verify
Check if Vulnerable:
Check Jsish version: jsish -v should show 3.5.0 if vulnerableCheck Version:
jsish -vVerify Fix Applied:
After upgrade, jsish -v should show 3.5.1 or later📡 Detection & Monitoring
Log Indicators:
- Segmentation fault crashes in Jsish processes
- Abnormal memory usage patterns in Jsish
Network Indicators:
- Unusual network connections from Jsish processes
SIEM Query:
process_name:"jsish" AND (event_type:"crash" OR memory_usage:>threshold)