NovumOS EUVD-2026-23640

Attacker must have ability to execute code at Ring 3 user-mode privilege level on a NovumOS system running version prior to 0.24. The CVSS vector PR:N indicates no authentication is required once code execution is achieved, meaning even sandboxed or restricted user processes can invoke the vulnerable syscall. Exploitation requires knowledge of x86 architecture internals (IDT/GDT addressing, interrupt handling mechanisms) and ability to craft syscall invocations with specific memory range parameters targeting kernel structures. The AV:L (local attack vector) limits this to code running directly on the vulnerable system, not remotely exploitable over network. AC:L (low attack complexity) and UI:N (no user interaction) indicate exploitation is straightforward once local code execution exists. The vulnerability affects default NovumOS configurations with no special features or settings required - the MemoryMapRange syscall is part of the standard system call interface. Exploitation is limited to 32-bit x86 deployments only, as the vulnerability is architecture-specific to NovumOS's x86 implementation. Changed scope (S:C) indicates successful exploitation breaches the security boundary between user processes and kernel, affecting system-wide integrity beyond the exploiting process.

This vulnerability presents contradictory risk signals requiring careful interpretation. CVSS 9.0 (Critical) reflects the severe technical impact - complete privilege escalation from user to kernel mode with high confidentiality and integrity impact plus changed scope. The AV:L/PR:N vector indicates local access without authentication, meaning any code executing on the system (including sandboxed applications) could exploit this. However, real-world risk indicators paint a different picture: EPSS score of 0.01% (2nd percentile) suggests minimal observed exploitation interest in production environments, consistent with NovumOS being a niche educational/research operating system rather than enterprise-deployed software. CISA SSVC assessment confirms POC availability but marks exploitation as non-automatable, requiring attacker-customized code for each target environment. The absence from CISA KEV despite POC availability indicates this affects research systems rather than critical infrastructure. Primary risk exists for organizations actively developing or testing with NovumOS in security-sensitive contexts. The 'total' technical impact rating reflects kernel compromise, but practical deployment surface is extremely limited compared to mainstream operating systems. Priority should be immediate patching for active NovumOS users, but broader enterprise security teams can safely deprioritize this unless their development teams explicitly use this OS for embedded/research purposes.

An attacker with the ability to execute code on a NovumOS system (such as through a compromised user application or by running malicious software) invokes Syscall 15 (MemoryMapRange) to map the kernel's Interrupt Descriptor Table (IDT) into their user-mode address space. They then overwrite an interrupt handler entry to point to attacker-controlled shellcode and trigger that interrupt (e.g., via division by zero or software interrupt instruction), causing the CPU to execute their code in kernel context (Ring 0) with full system privileges. CISA SSVC framework confirms POC code availability, making technical reproduction straightforward for attackers with local system access and basic x86 assembly knowledge.