CVE-2026-40572: NovumOS Privilege Escalation Vulnerability

CVE-2026-40572 Overview

CVE-2026-40572 is a critical privilege escalation vulnerability in NovumOS, a custom 32-bit operating system written in Zig and x86 Assembly. The vulnerability exists in Syscall 15 (MemoryMapRange), which allows Ring 3 user-mode processes to map arbitrary virtual address ranges into their address space without proper validation against protected kernel memory regions.

This flaw enables local attackers to map and modify critical kernel structures including the Interrupt Descriptor Table (IDT), Global Descriptor Table (GDT), Task State Segment (TSS), and page tables. By manipulating kernel interrupt handlers, an attacker can escalate privileges from user mode to kernel context, gaining complete control over the operating system.

Critical Impact

Local attackers can achieve full privilege escalation from user mode (Ring 3) to kernel context (Ring 0) by exploiting inadequate memory mapping validation, potentially compromising the entire system.

Affected Products

• NovumOS versions prior to 0.24

Discovery Timeline

• 2026-04-18 - CVE CVE-2026-40572 published to NVD
• 2026-04-20 - Last updated in NVD database

Technical Details for CVE-2026-40572

Vulnerability Analysis

This vulnerability stems from a fundamental flaw in the system call interface that handles memory mapping operations. The MemoryMapRange syscall (Syscall 15) accepts user-supplied virtual address ranges and maps them into the calling process's address space. However, the implementation fails to implement proper boundary checks to prevent user-mode processes from mapping kernel-reserved memory regions.

In a properly secured operating system, kernel structures such as the IDT, GDT, TSS, and page tables must remain inaccessible to user-mode processes. These structures control critical system operations including interrupt handling, memory segmentation, task switching, and virtual-to-physical address translation. The missing validation allows a malicious user-mode process to request mapping of these protected regions, effectively granting read and write access to kernel memory.

Once an attacker gains write access to the IDT, they can modify interrupt handler pointers to redirect execution flow to attacker-controlled code when specific interrupts occur. This classic privilege escalation technique allows arbitrary code execution in kernel context.

Root Cause

The root cause is classified under CWE-269 (Improper Privilege Management). The MemoryMapRange syscall implementation lacks validation logic to check requested memory ranges against a blocklist of forbidden kernel regions. The kernel does not verify whether the requested virtual address range overlaps with critical kernel structures before completing the mapping operation. This absence of privilege boundary enforcement allows user-mode processes to access memory that should be exclusively reserved for kernel operations.

Attack Vector

The attack requires local access to the system. An attacker with the ability to execute user-mode code on a NovumOS system can craft a malicious process that invokes Syscall 15 with parameters specifying kernel memory regions. The attack chain typically involves:

1. Identifying the virtual addresses of kernel structures (IDT, GDT, TSS, or page tables) through information disclosure or known fixed addresses
2. Calling MemoryMapRange to map the target kernel structure into the process's address space
3. Modifying interrupt handler entries in the IDT to point to attacker-controlled code
4. Triggering the modified interrupt to execute code with kernel privileges

The vulnerability enables complete compromise of system integrity and confidentiality, as the attacker gains Ring 0 execution privileges. For detailed technical information, refer to the GitHub Security Advisory GHSA-rg7m-6vh7-f4v2.

Detection Methods for CVE-2026-40572

Indicators of Compromise

• Unexpected or anomalous calls to Syscall 15 (MemoryMapRange) requesting addresses in kernel memory space
• User-mode processes with mapped memory regions overlapping known kernel structure addresses (IDT, GDT, TSS ranges)
• Modifications to interrupt handler entries in the IDT that point to user-space addresses
• Unexpected privilege elevation of user-mode processes to kernel context

Detection Strategies

• Monitor syscall activity for Syscall 15 invocations with address ranges outside the expected user-space boundaries
• Implement kernel integrity monitoring to detect unauthorized modifications to IDT, GDT, TSS, and page table entries
• Deploy runtime analysis tools to flag user-mode processes that successfully map kernel-reserved memory regions
• Review system logs for unusual process behavior patterns indicative of privilege escalation attempts

Monitoring Recommendations

• Enable detailed syscall logging to capture all memory mapping operations and their parameters
• Implement periodic integrity checks on critical kernel structures to detect tampering
• Configure alerting for any detected memory mapping requests targeting addresses below the user-space boundary
• Monitor for unusual process privilege transitions that may indicate successful exploitation

How to Mitigate CVE-2026-40572

Immediate Actions Required

• Upgrade NovumOS to version 0.24 or later immediately to address this vulnerability
• Audit any systems running vulnerable versions for signs of compromise or exploitation
• Restrict local access to NovumOS systems to trusted users only until patching is complete
• Consider temporarily disabling or restricting access to Syscall 15 functionality if patching cannot be performed immediately

Patch Information

The vulnerability has been fixed in NovumOS version 0.24. The patch implements proper validation in the MemoryMapRange syscall to check requested address ranges against forbidden kernel memory regions before completing the mapping operation. System administrators should update to version 0.24 by downloading the release from the official GitHub repository.

Workarounds

• Limit local system access to only trusted users who require it for legitimate purposes
• Implement application-level controls to restrict which processes can invoke memory mapping syscalls
• Deploy monitoring solutions to detect and alert on potential exploitation attempts while awaiting patch deployment
• Consider running critical workloads on patched or alternative systems until the vulnerable NovumOS instances can be updated

# Verify NovumOS version to confirm patched status
# Ensure version is 0.24 or later
cat /etc/novumos-release
# Expected output: NovumOS v0.24 or higher