CVE-2026-89655

Invalid kernel memory access via capability-flush race

Published Sep 11, 2026 · Updated Sep 11, 2026

A use-after-free in Linux CephFS kernels before 6.12.109, 6.18.50, and 7.2.4 allows attackers to trigger an invalid memory access. __kick_flushing_caps() drops i_ceph_lock while retaining its current list entry, which handle_cap_flush_ack() can detach and free before iteration resumes. Active CephFS capability flushing and a sufficiently fast MDS acknowledgment are required; no broader confidentiality or integrity impact is reported.

CVSS severityUnavailable
Unscored
EPSS probability0.70%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

A use-after-free in Linux CephFS kernels before 6.12.109, 6.18.50, and 7.2.4 allows attackers to trigger an invalid memory access. __kick_flushing_caps() drops i_ceph_lock while retaining its current list entry, which handle_cap_flush_ack() can detach and free before iteration resumes. Active CephFS capability flushing and a sufficiently fast MDS acknowledgment are required; no broader confidentiality or integrity impact is reported.

The record

CVE
CVE-2026-89655
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 <2701431aa3cc8b23efe6890182e7b04f5e76fab5
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2dba24dcd5050be4b7b119e6f0b01f62203b5d26
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7af4c4f01305b0935adf6d4301b1ec407025485d
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <fe46746087b5b9c5bb2d022df6c7819218494ced

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 <2701431aa3cc8b23efe6890182e7b04f5e76fab5; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2dba24dcd5050be4b7b119e6f0b01f62203b5d26; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7af4c4f01305b0935adf6d4301b1ec407025485d; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <fe46746087b5b9c5bb2d022df6c7819218494ced

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

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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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