---
id: CVE-2026-89520
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  sched/core: Make core-sched flips wait for in-flight selections

  Core scheduling's pick_next_task() operates on all sibling rqs under one
  acquisition of the shared core…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  sched/core: Make core-sched flips wait for in-flight selections

  Core scheduling's pick_next_task() operates on all sibling rqs under one
  acquisition of the shared core…
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'
cwe:
  - CWE-366
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 539f65125d20aacab54d02d77f10a839f45b09dc <
    3e2511bffa93a639774a99e392181e21d28677e2
  - >-
    Linux >= 539f65125d20aacab54d02d77f10a839f45b09dc <
    9d69422ddaa13526c2223444e237d948d6e44728
  - >-
    Linux >= 539f65125d20aacab54d02d77f10a839f45b09dc <
    23eda24f325a6e6d686d30ec75f2e9d6745e2015
  - >-
    Linux >= 539f65125d20aacab54d02d77f10a839f45b09dc <
    f3629c63a4af3e491381780bc6c123cb498c4c40
  - Linux 5.14
published: '2026-09-11'
updated: '2026-10-03'
sourceUpdated: '2026-10-03T11:17:42.710'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89520'
references:
  - url: 'https://git.kernel.org/stable/c/23eda24f325a6e6d686d30ec75f2e9d6745e2015'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/3e2511bffa93a639774a99e392181e21d28677e2'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9d69422ddaa13526c2223444e237d948d6e44728'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f3629c63a4af3e491381780bc6c123cb498c4c40'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89520.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89520'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532271'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89520'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89520'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89520.mbox
  - url: 'https://git.kernel.org/stable/c/a2a16896ed53046f275f56a6cd8ca3fb6f12c4f3'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00168
epssPercentile: 0.06172
scores:
  nvd: 7.8
  vendor: 5.5
  cna: 7.8
ingestedAt: '2026-09-14T15:23:07.475Z'
---

## Overview

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

sched/core: Make core-sched flips wait for in-flight selections

Core scheduling's pick_next_task() operates on all sibling rqs under one
acquisition of the shared core-wide lock. A ->pick_task() that releases the
rq lock leaves every sibling __lock momentarily free, letting
__sched_core_flip(false) complete mid-selection and rebind rq_lockp() under
it. The selection resumes on the split locks, touching sibling state it no
longer protects, and __schedule() finally releases a lock that was never
taken while leaking the one that was.

Count in-flight core-wide selections in the leader's rq->core_pick_in_flight
and make __sched_core_flip() wait for the count to drain. The count only
changes under the shared lock, which the flip holds while sampling, so no
other ordering is needed. The wait can repeat while selections overlap, but
the flip backs off between samples and flips are rare cookie-lifetime
events.

sched_core_cpu_deactivate() moves the count to the new leader - a stale copy
left behind would bias it forever if that CPU later returns as its own
leader.

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89520.json)