CVE-2025-65570 is a critical type confusion vulnerability identified in jsish version 2.0, a lightweight JavaScript interpreter often embedded in applications and devices. The vulnerability is triggered during the execution of the OP_NEXT opcode, which is part of the bytecode interpreter handling for-in loops. Specifically, when an instanceof expression uses an array element access as the left-hand operand inside a for-in loop, the interpreter's instructions leave an additional array reference on the stack instead of consuming it during the OP_INSTANCEOF operation. This leftover reference causes the subsequent OP_NEXT opcode to misinterpret the array as an iterator object. Consequently, OP_NEXT reads the iterCmd function pointer from an invalid memory structure, leading to undefined behavior. Depending on the heap layout, this can cause a program crash or enable an attacker to execute arbitrary code with the privileges of the vulnerable process. The vulnerability is classified under CWE-843 (Type Confusion), which typically results in memory corruption and potential code execution. The CVSS v3.1 base score of 9.8 reflects the vulnerability's critical nature: it is remotely exploitable over the network (AV:N), requires no privileges (PR:N), no user interaction (UI:N), and impacts confidentiality, integrity, and availability (C:H/I:H/A:H). Although no patches or known exploits are currently reported, the high severity and straightforward exploitation vector make this a pressing security concern for any environment using jsish 2.0.

For European organizations, the impact of CVE-2025-65570 can be severe. Exploitation could lead to full system compromise, data breaches, or service disruptions. Organizations embedding jsish 2.0 in their products or internal tools may face risks of unauthorized code execution, potentially allowing attackers to steal sensitive data, manipulate system behavior, or disrupt operations. Critical infrastructure sectors such as energy, telecommunications, and finance that rely on embedded scripting engines could experience outages or targeted attacks. The vulnerability's network exploitability and lack of authentication requirements increase the risk of widespread attacks, especially in interconnected environments. Additionally, supply chain risks arise if third-party vendors use vulnerable jsish versions, potentially affecting European companies indirectly. The absence of known exploits currently provides a window for proactive mitigation, but the critical severity demands immediate attention to prevent future exploitation.

Given the absence of an official patch at this time, European organizations should implement several specific mitigations: 1) Conduct an inventory to identify all instances of jsish 2.0 usage within software and embedded systems. 2) Where possible, disable or restrict the use of scripting features that rely on the vulnerable OP_NEXT and OP_INSTANCEOF bytecode operations, particularly for-in loops involving instanceof expressions with array elements. 3) Employ runtime application self-protection (RASP) or memory protection mechanisms such as Control Flow Integrity (CFI) and Address Space Layout Randomization (ASLR) to reduce exploitation success. 4) Monitor application logs and system behavior for crashes or anomalous activity indicative of exploitation attempts. 5) Engage with software vendors and open-source communities to track patch releases and apply updates promptly once available. 6) For critical systems, consider isolating or sandboxing components using jsish to limit the blast radius of a potential compromise. 7) Implement network-level protections such as firewalls and intrusion detection systems tuned to detect exploitation patterns targeting jsish vulnerabilities. These targeted steps go beyond generic advice by focusing on the specific nature of the vulnerability and the operational context of jsish.