---
id: CVE-2025-40291
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  io_uring: fix regbuf vector size truncation

  There is a report of io_estimate_bvec_size() truncating the calculated
  number of segments that leads to corruption issues
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  io_uring: fix regbuf vector size truncation

  There is a report of io_estimate_bvec_size() truncating the calculated
  number of segments that leads to corruption issues. …
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
published: '2025-12-08'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T22:10:00.210'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-40291'
references:
  - url: 'https://git.kernel.org/stable/c/146eb58629f45f8297e83d69e64d4eea4b28d972'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/826ce37a842633efe1bb763e4b13045d74060d72'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00144
epssPercentile: 0.03295
ingestedAt: '2026-10-14T23:00:02.015Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

io_uring: fix regbuf vector size truncation

There is a report of io_estimate_bvec_size() truncating the calculated
number of segments that leads to corruption issues. Check it doesn't
overflow "int"s used later. Rough but simple, can be improved on top.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.