CVE-2025-38366 in Linux
Summary
by MITRE • 07/25/2025
In the Linux kernel, the following vulnerability has been resolved:
LoongArch: KVM: Check validity of "num_cpu" from user space
The maximum supported cpu number is EIOINTC_ROUTE_MAX_VCPUS about irqchip EIOINTC, here add validation about cpu number to avoid array pointer overflow.
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Analysis
by VulDB Data Team • 12/23/2025
The vulnerability CVE-2025-38366 addresses a critical validation issue within the Linux kernel's KVM implementation for LoongArch architecture. This flaw specifically relates to the handling of virtual CPU allocation in virtual machine environments where the kernel fails to properly validate the number of CPUs requested from user space. The vulnerability exists in the interrupt controller implementation known as EIOINTC, which has a defined maximum supported virtual CPU count of EIOINTC_ROUTE_MAX_VCPUS. When user space applications provide an invalid cpu number parameter during KVM initialization or configuration, the kernel does not perform adequate bounds checking, creating a potential pathway for memory corruption through array pointer overflow conditions.
This security gap represents a classic case of insufficient input validation that can lead to arbitrary code execution or system instability. The technical flaw manifests when the KVM subsystem processes user-provided cpu count values without ensuring they fall within the acceptable range defined by the hardware-specific interrupt controller capabilities. The absence of proper validation allows malicious or malformed input to bypass kernel safety mechanisms, potentially enabling attackers to manipulate memory layouts and execute unauthorized code within the hypervisor context. This vulnerability directly impacts the integrity of the virtualization layer and can compromise the isolation guarantees that KVM is designed to maintain between guest operating systems and the host system.
The operational impact of CVE-2025-38366 extends beyond simple memory corruption, as it can enable privilege escalation attacks within virtualized environments where attackers might leverage the vulnerability to gain elevated privileges or disrupt system operations. When exploited, the array pointer overflow could result in denial of service conditions, data corruption, or potentially full system compromise depending on the execution context. The vulnerability is particularly concerning in cloud computing and virtualization environments where multiple tenants share the same physical hardware, as it could allow one guest to affect others or the host system itself. The attack surface is primarily limited to systems running KVM with LoongArch architecture and utilizing the EIOINTC interrupt controller implementation, making it a targeted issue within specific hardware configurations.
Mitigation strategies for this vulnerability require immediate kernel updates that implement proper validation of cpu number parameters against the EIOINTC_ROUTE_MAX_VCPUS limit. System administrators should prioritize patching affected systems and monitoring for any anomalous behavior that might indicate exploitation attempts. Additional defensive measures include implementing strict input validation at the application level before passing parameters to KVM interfaces, utilizing hypervisor security modules that can detect and prevent malformed cpu allocation requests, and conducting regular security audits of virtualization configurations. The fix aligns with security best practices outlined in CWE-129 and CWE-787, which address issues related to insufficient input validation and out-of-bounds write vulnerabilities. Organizations should also consider implementing runtime monitoring solutions that can detect unusual patterns in cpu allocation requests and alert security teams to potential exploitation attempts. This vulnerability demonstrates the critical importance of proper input validation in hypervisor implementations and the potential consequences when such safeguards are missing from virtualization stack components.