Linux Kernel up to 6.18.50/7.2.3 Core Scheduling __sched_core_flip race condition

CVSS Meta Temp Score
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CTI Interest Score
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8.4$0-$5k0.00+

Summaryinfo

A vulnerability marked as very critical has been reported in Linux Kernel up to 6.18.50/7.2.3. This affects the function __sched_core_flip of the component Core Scheduling. The manipulation leads to race condition. This vulnerability is listed as CVE-2026-89520. The attack must be carried out locally. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as very critical, has been found in Linux Kernel up to 6.18.50/7.2.3. This issue affects the function __sched_core_flip of the component Core Scheduling. The manipulation with an unknown input leads to a race condition vulnerability. Using CWE to declare the problem leads to CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2026-89520 since 09/11/2026. The exploitation is known to be easy. An attack has to be approached locally. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/12/2026).

Upgrading to version 6.18.51, 7.2.4 or 7.3-rc1 eliminates this vulnerability. Applying the patch 9d69422ddaa13526c2223444e237d948d6e44728/23eda24f325a6e6d686d30ec75f2e9d6745e2015/f3629c63a4af3e491381780bc6c123cb498c4c40 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.8
VulDB Meta Temp Score: 8.4

VulDB Base Score: 8.8
VulDB Temp Score: 8.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Race condition
CWE: CWE-362
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.51/7.2.4/7.3-rc1
Patch: 9d69422ddaa13526c2223444e237d948d6e44728/23eda24f325a6e6d686d30ec75f2e9d6745e2015/f3629c63a4af3e491381780bc6c123cb498c4c40

Timelineinfo

09/11/2026 CVE reserved
09/11/2026 +0 days VulDB entry created
09/12/2026 +0 days Advisory disclosed
09/12/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89520 (🔒)
GCVE (CVE): GCVE-0-2026-89520
GCVE (VulDB): GCVE-100-402833

Entryinfo

Created: 09/12/2026 01:00
Changes: 09/12/2026 01:00 (59)
Complete: 🔍
Cache ID: 216::103

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