CVE-2025-40081: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-40081 is a vulnerability in the Linux kernel affecting the ARM SPE (Statistical Profiling Extension) performance monitoring subsystem, discovered and disclosed on October 28, 2025. The vulnerability specifically affects the PERF_IDX2OFF() function, where potential overflow could occur when handling large AUX buffer sizes greater than or equal to 2 GiB (NVD CVE, RedHat Security).

The vulnerability exists in the Linux kernel's performance monitoring subsystem, specifically in the ARM SPE implementation. The issue arises from improper handling of nrpages casting in the PERFIDX2OFF() function, which could lead to overflow when processing AUX buffer sizes of 2 GiB or larger. The vulnerability has been assigned a CVSS v3.1 score of 7.0, indicating moderate severity with the vector string CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H (RedHat Security).

The vulnerability affects multiple versions of Red Hat Enterprise Linux, including versions 8, 9, and 10, as well as their real-time kernel variants (kernel-rt). The impact is considered moderate, potentially allowing local attackers with low privileges to exploit the overflow condition in the performance monitoring subsystem (RedHat Security).

The vulnerability has been resolved by casting nr_pages to unsigned long to prevent overflow when handling large AUX buffer sizes. Affected systems should apply the appropriate kernel updates when available through their respective distribution channels (NVD CVE).