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.
Affected products
jsish: jsish
References2
- blog.mcsky.ro/writeups/2025/11/15/inline8-writeup.html ExploitThird Party Advisory
- blog.mcsky.ro/writeups/2025/11/15/inline8-writeup.html ExploitThird Party Advisory
Metrics
- CVSS 3.1
-
9.8
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 1% percentile: 45 · as of 11 November 2026
- CWE
- CWE-843
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