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.

CVSS 3.1

9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

0.5% chance of exploitation in the next 30 days; higher than 44% of CVEs (scores of 2026-10-25)

CWE

CWE-843

Published

2025-12-29

Modified

2026-10-13

Record from

the NVD, synced 2026-10-19

Affected

• jsish:jsish

References

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

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