CVE-2026-89756

Tasks-RCU stalls via unreported migration quiescence

Published Sep 11, 2026 · Updated Sep 11, 2026

Denial of service in affected Linux kernels allows attackers to stall Tasks-RCU grace periods for minutes via large migration batches. In migrate_pages_batch(), cond_resched() becomes a no-op on PREEMPTION kernels, so repeated folio unmapping never reports a Tasks-RCU quiescent state. The condition arises on KVM hosts when expensive MMU-notifier invalidations keep a migration task such as kcompactd running through a long batch.

CVSS severityUnavailable
Unscored
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in affected Linux kernels allows attackers to stall Tasks-RCU grace periods for minutes via large migration batches. In migrate_pages_batch(), cond_resched() becomes a no-op on PREEMPTION kernels, so repeated folio unmapping never reports a Tasks-RCU quiescent state. The condition arises on KVM hosts when expensive MMU-notifier invalidations keep a migration task such as kcompactd running through a long batch.

The record

CVE
CVE-2026-89756
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <6.12.109
  2. Affected versionversion=0 <6.18.50
  3. Affected versionversion=0 <7.2.4
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4996a7bc01ef35570664854dac2530c604981039
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5dc0daff0341c6baba19c38f47d299ac831d7e99
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <66734981b4d3c105223a13c827c9c73be18d91ad
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <efe8f86c0916f0f74eea74ae21a3b37f728c6bad

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=0 <6.12.109; version=0 <6.18.50; version=0 <7.2.4; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4996a7bc01ef35570664854dac2530c604981039; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5dc0daff0341c6baba19c38f47d299ac831d7e99; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <66734981b4d3c105223a13c827c9c73be18d91ad; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <efe8f86c0916f0f74eea74ae21a3b37f728c6bad

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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