CVE-2026-89646

Host panic via leaked writeback inode reference

Published Sep 11, 2026 · Updated Sep 11, 2026

A reference leak in the Linux kernel's CephFS client allows local users with mount control to panic the host during unmount. When ceph_submit_write aborts after unmount starts, it redirties locked folios without releasing their wrbuffer and snap-context claims, so writepages_finish cannot drop the inode hold. The condition requires control of a CephFS kernel-client mount with dirty pages and can leave busy inodes that trigger a kernel BUG and full-node reboot.

CVSS severityUnavailable
Unscored
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A reference leak in the Linux kernel's CephFS client allows local users with mount control to panic the host during unmount. When ceph_submit_write aborts after unmount starts, it redirties locked folios without releasing their wrbuffer and snap-context claims, so writepages_finish cannot drop the inode hold. The condition requires control of a CephFS kernel-client mount with dirty pages and can leave busy inodes that trigger a kernel BUG and full-node reboot.

The record

CVE
CVE-2026-89646
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
admin

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=6.15
  2. Affected versionversion=fd7449d937e7fb3144770592927cf452bf66dbd3 <ac7a5a5385762df458d10cccc086a4e079be7409
  3. Affected versionversion=fd7449d937e7fb3144770592927cf452bf66dbd3 <c25aee9c630fb86f98d79eccb75765067079b972
  4. Affected versionversion=fd7449d937e7fb3144770592927cf452bf66dbd3 <ec32015a955c5d326c5e26610edfdcccd52f2314

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linuxversion=6.15; version=fd7449d937e7fb3144770592927cf452bf66dbd3 <ac7a5a5385762df458d10cccc086a4e079be7409; version=fd7449d937e7fb3144770592927cf452bf66dbd3 <c25aee9c630fb86f98d79eccb75765067079b972; version=fd7449d937e7fb3144770592927cf452bf66dbd3 <ec32015a955c5d326c5e26610edfdcccd52f2314

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)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

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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