CVE-2025-37815 is a vulnerability identified in the Linux kernel specifically affecting the handling of IRQ (Interrupt Request) handlers within the 'misc: microchip: pci1xxxx' driver component. The issue manifests as a kernel panic during the registration of IRQ handlers. The root cause lies in improper synchronization and interrupt state management when handling generated IRQs. Initially, a patch attempted to fix this by replacing the call to 'generic_handle_irq' with 'handle_nested_irq'. However, this introduced a regression where the kernel panic persisted because the system failed to locate the registered handler after determining the GPIO that triggered the interrupt. The correct fix involves acquiring a spinlock and saving the current interrupt state before invoking 'generic_handle_irq', ensuring safe and consistent interrupt handling. This vulnerability affects multiple Linux kernel versions identified by specific commit hashes. While no known exploits are currently reported in the wild, the flaw can cause system instability or denial of service due to kernel panics triggered by IRQ handling failures. The vulnerability does not have an assigned CVSS score yet, but its impact on system availability and stability is significant, especially for systems relying on the affected driver for hardware interrupt management.

For European organizations, this vulnerability poses a risk primarily to systems running affected Linux kernel versions with the 'misc: microchip: pci1xxxx' driver enabled. The kernel panic triggered by this flaw can lead to unexpected system crashes, resulting in denial of service conditions. This can disrupt critical infrastructure, industrial control systems, or embedded devices that depend on stable Linux kernel operations. Organizations in sectors such as manufacturing, telecommunications, and critical infrastructure that utilize Linux-based systems with microchip PCI devices may experience operational interruptions. Additionally, the instability could be exploited indirectly by attackers to cause service outages or to facilitate further attacks by destabilizing systems. Although no active exploits are known, the potential for denial of service and system reliability degradation makes this a concern for maintaining continuous operations and service availability in European enterprises.

To mitigate this vulnerability, European organizations should prioritize updating their Linux kernels to versions where this issue is resolved. Since the vulnerability is tied to specific driver code and kernel versions, applying the official patches or upgrading to the latest stable kernel release that includes the fix is critical. System administrators should audit their environments to identify systems running the affected kernel versions and verify if the 'misc: microchip: pci1xxxx' driver is in use. For embedded or specialized systems where kernel upgrades may be complex, backporting the patch or recompiling the kernel with the fix applied should be considered. Additionally, implementing robust monitoring for kernel panics and system crashes can help detect exploitation attempts or instability early. Organizations should also ensure that their incident response and recovery procedures can handle potential downtime caused by this vulnerability. Avoiding untrusted code execution and limiting access to systems with affected kernels can reduce the risk of exploitation.