CVE-2026-46066

Kernel panic via miscounted Ceph write extents

Published May 27, 2026 · Updated May 27, 2026

Off-by-one error in Linux kernel CephFS writeback allows local users to panic the kernel by writing encrypted files under memory pressure. ceph_process_folio_batch() increments num_ops for a new discontiguous extent before move_dirty_folio_in_page_array() allocates its ciphertext bounce buffer, but it does not undo that count when allocation fails. Triggering the mismatch requires fscrypt-enabled CephFS writes with noncontiguous dirty folios and enough memory pressure to fail the bounce-buffer allocation, causing a kernel crash.

CVSS severity5.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Off-by-one error in Linux kernel CephFS writeback allows local users to panic the kernel by writing encrypted files under memory pressure. ceph_process_folio_batch() increments num_ops for a new discontiguous extent before move_dirty_folio_in_page_array() allocates its ciphertext bounce buffer, but it does not undo that count when allocation fails. Triggering the mismatch requires fscrypt-enabled CephFS writes with noncontiguous dirty folios and enough memory pressure to fail the bounce-buffer allocation, causing a kernel crash.

The record

CVE
CVE-2026-46066
Published
May 27, 2026
Updated
May 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-193, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 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=6.6
  2. Affected versionversion=d55207717ded95c8f2760a30e93319fa313186e6 <6200f41d6fcf2ac7e24866431e381cbc914560e4
  3. Affected versionversion=d55207717ded95c8f2760a30e93319fa313186e6 <a0d9555bf9eaeba34fe6b6bb86f442fe08ba3842
  4. Affected versionversion=d55207717ded95c8f2760a30e93319fa313186e6 <ba12c1e578890f6337a415b7dedf476c6d455105

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.6; version=d55207717ded95c8f2760a30e93319fa313186e6 <6200f41d6fcf2ac7e24866431e381cbc914560e4; version=d55207717ded95c8f2760a30e93319fa313186e6 <a0d9555bf9eaeba34fe6b6bb86f442fe08ba3842; version=d55207717ded95c8f2760a30e93319fa313186e6 <ba12c1e578890f6337a415b7dedf476c6d455105

Published CVSS scores

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

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 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-193Off-by-one Error
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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