CVE-2025-65570: jsish — Exploit

Description

A type confusion in jsish 2.0 allows incorrect control flow during execution of the OP_NEXT opcode. When an “instanceof” expression uses an array element access as the left-hand operand inside a for-in loop, the instructions implementation leaves an additional array reference on the stack rather than consuming it during OP_INSTANCEOF. As a result, OP_NEXT interprets the array as an iterator object and reads the iterCmd function pointer from an invalid structure, potentially causing a crash or enabling code execution depending on heap layout.

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CVSS v3.1 Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness Type (CWE)

CWE-843 CWE-843

Affected Products

Vendor	Product	Versions
jsish	jsish	All

References

Exploits

https://blog.mcsky.ro/writeups/2025/11/15/inline8-writeup.html https://blog.mcsky.ro/writeups/2025/11/15/inline8-writeup.html

Frequently Asked Questions

What is CVE-2025-65570? +

A type confusion in jsish 2.0 allows incorrect control flow during execution of the OP_NEXT opcode. When an “instanceof” expression uses an array element access as the left-hand operand inside a for-in loop, the instructions implementation leaves an additional array reference on the stack rather than consuming it during OP_INSTANCEOF. As a result, OP_NEXT interprets the array as an iterator object and reads the iterCmd function pointer from an invalid structure, potentially causing a crash or enabling code execution depending on heap layout. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2025-65570? +

CVE-2025-65570 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately.

What products are affected by CVE-2025-65570? +

CVE-2025-65570 affects products from jsish, specifically: jsish. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-65570? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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