CVE-2025-62493
📋 TL;DR
This vulnerability in QuickJS engine allows attackers to read memory beyond allocated BigInt buffers during string conversion, potentially exposing sensitive heap data. It affects any application or system using vulnerable QuickJS versions for JavaScript execution. The risk is information disclosure of adjacent memory contents.
💻 Affected Systems
- QuickJS JavaScript Engine
📦 What is this software?
Quickjs by Quickjs Project
⚠️ Risk & Real-World Impact
Worst Case
Complete memory disclosure of sensitive data like encryption keys, passwords, or other application secrets stored in heap memory adjacent to BigInt objects.
Likely Case
Partial memory leak revealing application-specific data or internal state information that could aid further exploitation.
If Mitigated
Limited information disclosure with minimal impact if memory randomization and isolation techniques are employed.
🎯 Exploit Status
Exploitation requires precise control over BigInt creation and string conversion parameters to trigger the off-by-one calculation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown specific version - check QuickJS changelog for fix
Vendor Advisory: https://bellard.org/quickjs/Changelog
Restart Required: No
Instructions:
1. Check QuickJS changelog for fix details. 2. Update to patched version. 3. Recompile applications using QuickJS. 4. No restart needed for embedded library updates.
🔧 Temporary Workarounds
Disable BigInt operations
allDisable BigInt support in QuickJS configuration if not required
Configure QuickJS build without BigInt support
🧯 If You Can't Patch
- Implement memory isolation techniques to limit impact of heap reads
- Monitor for unusual BigInt conversion patterns in application logs
🔍 How to Verify
Check if Vulnerable:
Check QuickJS version against patched releases in changelogCheck Version:
Check application documentation for embedded QuickJS version or compile with version outputVerify Fix Applied:
Test BigInt string conversion with edge cases (127-bit BigInt, radix 32) and verify no crashes or memory errors📡 Detection & Monitoring
Log Indicators:
- Memory access violations
- Segmentation faults in QuickJS processes
- Unusual BigInt conversion patterns
Network Indicators:
- None - this is a local memory corruption vulnerability
SIEM Query:
Process crashes containing 'quickjs' or 'segmentation fault' in stack traces