CVE-2020-23259
📋 TL;DR
This vulnerability in Jsish (a JavaScript interpreter for embedded systems) allows attackers to cause denial of service through a NULL pointer dereference in the Jsi_Strlen function. Systems running Jsish v3.0.11 or earlier are affected, particularly embedded devices and applications using this interpreter.
💻 Affected Systems
- Jsish
📦 What is this software?
Jsish by Jsish
⚠️ Risk & Real-World Impact
Worst Case
Complete service disruption causing Jsish interpreter to crash, potentially affecting the entire application or device functionality.
Likely Case
Application crash or hang requiring restart, leading to temporary service unavailability.
If Mitigated
Minimal impact if proper input validation and error handling are implemented at application layer.
🎯 Exploit Status
Proof of concept available in GitHub issue. Exploitation requires ability to pass malicious input to Jsi_Strlen function.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v3.0.12 and later
Vendor Advisory: https://jsish.org/fossil/jsi2/tktview?name=b6bb078e00
Restart Required: Yes
Instructions:
1. Download latest Jsish version from official repository. 2. Replace existing Jsish installation. 3. Restart any applications using Jsish.
🔧 Temporary Workarounds
Input Validation
allImplement strict input validation for all data passed to Jsish interpreter functions
Process Isolation
allRun Jsish in isolated process/container to limit crash impact
🧯 If You Can't Patch
- Implement application-level input sanitization for all Jsish function calls
- Deploy monitoring to detect and restart crashed Jsish processes automatically
🔍 How to Verify
Check if Vulnerable:
Check Jsish version: jsish -v or examine installed package versionCheck Version:
jsish -vVerify Fix Applied:
Verify version is v3.0.12 or later and test with known exploit payloads📡 Detection & Monitoring
Log Indicators:
- Segmentation fault errors
- Jsi_Strlen function failures
- Unexpected Jsish process termination
Network Indicators:
- Unusual input patterns to applications using Jsish
SIEM Query:
process_name:"jsish" AND (event_type:"crash" OR error_message:"segmentation fault")