CVE-2025-62494
📋 TL;DR
A type confusion vulnerability in QuickJS engine's string addition operation allows attackers to trigger callbacks that modify operand types in memory, leading to memory corruption. This can result in arbitrary code execution within the QuickJS runtime. Affects any application or system using vulnerable versions of QuickJS.
💻 Affected Systems
- QuickJS
- Applications embedding QuickJS
📦 What is this software?
Quickjs by Quickjs Project
⚠️ Risk & Real-World Impact
Worst Case
Arbitrary code execution with QuickJS runtime privileges, potentially leading to full system compromise if QuickJS runs with elevated permissions.
Likely Case
Memory corruption leading to application crashes, denial of service, or limited code execution within the sandboxed JavaScript environment.
If Mitigated
Application crashes or denial of service if memory corruption is contained by sandboxing or privilege restrictions.
🎯 Exploit Status
Exploitation requires crafting malicious JavaScript that triggers the type confusion during string concatenation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check QuickJS changelog for specific fixed version
Vendor Advisory: https://bellard.org/quickjs/Changelog
Restart Required: Yes
Instructions:
1. Check current QuickJS version
2. Update to latest version from official repository
3. Recompile and reinstall if using source
4. Restart applications using QuickJS
🔧 Temporary Workarounds
Disable QuickJS if not essential
allRemove or disable QuickJS from systems where it's not required
# For package managers: apt remove quickjs or equivalent
🧯 If You Can't Patch
- Sandbox QuickJS execution with minimal privileges
- Implement input validation to reject suspicious JavaScript patterns
🔍 How to Verify
Check if Vulnerable:
Check QuickJS version against patched version in changelogCheck Version:
quickjs --version or check embedded version in applicationsVerify Fix Applied:
Verify QuickJS version is updated and test with known safe JavaScript operations📡 Detection & Monitoring
Log Indicators:
- Application crashes with QuickJS memory errors
- Unusual JavaScript execution patterns
Network Indicators:
- Unexpected JavaScript payloads targeting QuickJS endpoints
SIEM Query:
Process execution: quickjs OR Application logs containing QuickJS memory errors