CVE-2025-65570
📋 TL;DR
A type confusion vulnerability in jsish 2.0 allows incorrect control flow during execution of the OP_NEXT opcode. When an 'instanceof' expression uses array element access inside a for-in loop, the implementation leaves an extra array reference on the stack, causing OP_NEXT to misinterpret it as an iterator object and potentially read function pointers from invalid memory structures. This affects systems running vulnerable versions of jsish, potentially leading to crashes or remote code execution.
💻 Affected Systems
- jsish
📦 What is this software?
Jsish by Jsish
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with full system compromise, allowing attackers to execute arbitrary code with the privileges of the jsish process.
Likely Case
Application crash leading to denial of service, with potential for memory corruption that could be leveraged for code execution depending on heap layout.
If Mitigated
Application crash with no code execution if exploit attempts fail due to heap randomization or other mitigations.
🎯 Exploit Status
Exploitation requires specific JavaScript code patterns but can be triggered remotely if jsish processes untrusted input. The writeup provides technical details that could facilitate weaponization.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Unknown
Restart Required: No
Instructions:
Check for official patches from jsish maintainers. If unavailable, consider upgrading to a newer version if one exists, or apply workarounds.
🔧 Temporary Workarounds
Input Validation
allValidate and sanitize all JavaScript input to prevent malicious patterns from reaching the jsish interpreter.
Sandbox Execution
allRun jsish in a sandboxed environment with limited privileges to contain potential exploitation.
🧯 If You Can't Patch
- Isolate jsish instances from critical systems and network access
- Implement strict input validation and filtering for JavaScript code processed by jsish
🔍 How to Verify
Check if Vulnerable:
Check if jsish version is 2.0. Review application code for patterns matching the vulnerability description.Check Version:
jsish -vVerify Fix Applied:
Verify jsish version has been updated beyond 2.0 or that workarounds are properly implemented.📡 Detection & Monitoring
Log Indicators:
- Unexpected crashes of jsish processes
- Memory access violation errors in system logs
Network Indicators:
- Unusual network traffic to/from jsish processes
SIEM Query:
Process:jsish AND (EventID:1000 OR EventID:1001) OR Memory:AccessViolation