CVE-2026-64600Public exploit

Local root escalation via stale XFS mapping

Published Jul 23, 2026 · Updated Jul 23, 2026

Race condition in Linux Kernel 4.11 and later allows local users to gain root by racing direct writes on reflink-enabled XFS. After xfs_reflink_fill_cow_hole reacquires ILOCK, xfs_bmap_trim_cow checks refcounts with a stale data-fork block mapping, so an O_DIRECT write reaches the original shared block. Exploitation requires read access to a protected target, a writable scratch path on the same reflink-enabled XFS filesystem, and no victim interaction.

CVSS severity7.8
High
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Linux Kernel 4.11 and later allows local users to gain root by racing direct writes on reflink-enabled XFS. After xfs_reflink_fill_cow_hole reacquires ILOCK, xfs_bmap_trim_cow checks refcounts with a stale data-fork block mapping, so an O_DIRECT write reaches the original shared block. Exploitation requires read access to a protected target, a writable scratch path on the same reflink-enabled XFS filesystem, and no victim interaction.

The record

CVE
CVE-2026-64600
Published
Jul 23, 2026
Updated
Jul 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-362, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 23, 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=3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 <206c09b04dc5469c7ff14d8aceff2d47c88078d9
  2. Affected versionversion=3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 <2f4acd0fcd862e22eab45690ec2c08c80b6ef2e7
  3. Affected versionversion=3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 <44f891bc088958399eec27f7604928694aa35581
  4. Affected versionversion=3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 <e705d81a7193dd19e69b8e2bad4696d78a4ea075
  5. Affected versionversion=4.11

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 <206c09b04dc5469c7ff14d8aceff2d47c88078d9; version=3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 <2f4acd0fcd862e22eab45690ec2c08c80b6ef2e7; version=3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 <44f891bc088958399eec27f7604928694aa35581; version=3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 <e705d81a7193dd19e69b8e2bad4696d78a4ea075; version=4.11

Published CVSS scores

7.8Linux Kernel CVE TeamCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 exploitPublished

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1068Exploitation for Privilege Escalation

Public exploit references

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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