CVE-2025-39879

Kernel crash via unshifted NULL folio entries

Published Sep 23, 2025 · Updated Sep 23, 2025

NULL pointer dereference in the Linux Ceph filesystem allows local users to crash the kernel during writeback failures. ceph_process_folio_batch() leaves NULL entries in a folio_batch when error paths bypass ceph_shift_unused_folios_left(), and folio release later dereferences them. Reachability requires local access to an active Ceph filesystem and a writeback failure; the documented consequence is an availability-only kernel crash.

CVSS severity5.5
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in the Linux Ceph filesystem allows local users to crash the kernel during writeback failures. ceph_process_folio_batch() leaves NULL entries in a folio_batch when error paths bypass ceph_shift_unused_folios_left(), and folio release later dereferences them. Reachability requires local access to an active Ceph filesystem and a writeback failure; the documented consequence is an availability-only kernel crash.

The record

CVE
CVE-2025-39879
Published
Sep 23, 2025
Updated
Sep 23, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 23, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 23, 2025Record 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=ce80b76dd32764cc914975777e058d4fae4f0ea0 <289b6615cf553d98509a9b273195d9936da1cfb2
  3. Affected versionversion=ce80b76dd32764cc914975777e058d4fae4f0ea0 <cce7c15faaac79b532a07ed6ab8332280ad83762

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.15; version=ce80b76dd32764cc914975777e058d4fae4f0ea0 <289b6615cf553d98509a9b273195d9936da1cfb2; version=ce80b76dd32764cc914975777e058d4fae4f0ea0 <cce7c15faaac79b532a07ed6ab8332280ad83762

Published CVSS scores

5.5CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
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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