CVE-2020-23306
📋 TL;DR
CVE-2020-23306 is a critical stack-based buffer overflow vulnerability in JerryScript's regular expression engine that allows remote code execution. Attackers can exploit this by providing specially crafted regular expressions to trigger the overflow. This affects any application or device using vulnerable versions of JerryScript for JavaScript execution.
💻 Affected Systems
- JerryScript JavaScript engine
📦 What is this software?
Jerryscript by Jerryscript
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with arbitrary code execution, potentially leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Remote code execution leading to application compromise, data exfiltration, or lateral movement within the network.
If Mitigated
Application crash or denial of service if exploit attempts are blocked by security controls.
🎯 Exploit Status
The vulnerability is in a core parsing function and requires only crafted regular expression input. Public GitHub issue demonstrates the crash condition.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: JerryScript 2.3.0 and later
Vendor Advisory: https://github.com/jerryscript-project/jerryscript/issues/3753
Restart Required: Yes
Instructions:
1. Update JerryScript to version 2.3.0 or later. 2. Recompile any applications using JerryScript. 3. Restart affected services or devices.
🔧 Temporary Workarounds
Input validation for regular expressions
allImplement strict validation and sanitization of regular expression inputs before passing to JerryScript
Memory protection controls
linuxEnable ASLR, stack canaries, and DEP/NX bit to make exploitation more difficult
echo 2 > /proc/sys/kernel/randomize_va_space
gcc -fstack-protector-all -z noexecstack -o program program.c
🧯 If You Can't Patch
- Network segmentation to isolate JerryScript applications from untrusted networks
- Implement WAF rules to block suspicious regular expression patterns
🔍 How to Verify
Check if Vulnerable:
Check JerryScript version: if version is 2.2.0 or earlier, system is vulnerable. Test with crafted regex: /^(a+)+$/ against long 'a' strings.Check Version:
jerry --version or check build configuration for embedded versionsVerify Fix Applied:
Verify JerryScript version is 2.3.0 or later. Test the same regex pattern that previously caused crashes.📡 Detection & Monitoring
Log Indicators:
- Segmentation fault crashes in JerryScript processes
- Abnormal memory usage patterns
- Repeated regex processing failures
Network Indicators:
- Unusual network traffic from JerryScript applications
- Requests containing complex or malformed regular expressions
SIEM Query:
process.name:"jerry" AND (event.action:"segmentation_fault" OR memory.usage > 90%)