CVE-2025-62490
📋 TL;DR
This CVE describes a use-after-free vulnerability in QuickJS's object printing functions. When printing arrays, maps, or sets, attacker-defined callbacks can modify the data structure during iteration, causing memory corruption. This affects any application using vulnerable QuickJS versions for JavaScript execution.
💻 Affected Systems
- QuickJS JavaScript engine
📦 What is this software?
Quickjs by Quickjs Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or service disruption.
Likely Case
Application crash leading to denial of service, with potential for memory corruption and information disclosure.
If Mitigated
Limited impact if proper sandboxing and input validation are in place, but still risk of crashes.
🎯 Exploit Status
Exploitation requires triggering object printing with malicious callbacks. The vulnerability is in core printing logic, making exploitation feasible but requiring specific conditions.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check QuickJS changelog for specific version (not specified in provided references)
Vendor Advisory: https://bellard.org/quickjs/Changelog
Restart Required: Yes
Instructions:
1. Check QuickJS changelog for fixed version. 2. Update QuickJS to latest patched version. 3. Recompile and redeploy any applications using QuickJS. 4. Restart affected services.
🔧 Temporary Workarounds
Disable object printing
allModify application code to avoid calling object printing functions on untrusted data
# Modify application source code to avoid js_print_object calls
Input sanitization
allValidate and sanitize all JavaScript input to prevent malicious callback execution
# Implement strict input validation before passing to QuickJS
🧯 If You Can't Patch
- Isolate QuickJS instances in containers or sandboxes to limit blast radius
- Implement network segmentation to restrict access to vulnerable services
🔍 How to Verify
Check if Vulnerable:
Check QuickJS version against changelog. If using embedded version, check application dependencies.Check Version:
qjs --version or check build configuration if embeddedVerify Fix Applied:
Verify QuickJS version is updated to patched version and test object printing functionality.📡 Detection & Monitoring
Log Indicators:
- Application crashes with memory corruption errors
- Unexpected process termination
Network Indicators:
- Unusual JavaScript payloads containing object printing patterns
SIEM Query:
Process termination events from QuickJS applications OR memory access violation alerts