CVE-2026-90383 addresses a vulnerability in the Linux kernel's SGI-GRU subsystem where the GRU TLB miss handler performed page-table walks in interrupt context without holding page-table locks or references to mapped pages. This unsafe behavior also involved using a kernel page-table accessor on user page tables and only supported PMD-level large mappings on x86-64. The remediation removes the direct walker and reroutes interrupt faults to user polling mode, allowing existing fallback mechanisms to handle retries in process context. Additionally, a now-obsolete mmap-lock failure statistic was removed.

The vulnerability could allow unauthorized access or modification of memory due to unsafe page-table walks without proper synchronization, potentially leading to confidentiality, integrity, and availability impacts. The CVSS score of 7.8 reflects high severity with local attack vector, low complexity, low privileges required, no user interaction, and high impact on confidentiality, integrity, and availability.

A fix has been implemented in the Linux kernel that removes the unsafe page-table walking behavior and changes interrupt fault handling to user polling mode. Users should update to the patched kernel version containing this fix. Since no specific patch version is provided, consult the official Linux kernel advisories for the fixed versions and apply updates accordingly.