CVE-2026-64378

Local kernel compromise via writeback unmount race

Published Jul 25, 2026 · Updated Jul 25, 2026

Use-after-free in Linux Kernel writeback allows local users to crash or compromise the host during container filesystem unmount. The gap after inode_prepare_wbs_switch() and before wb_queue_isw() lets unmount drain an empty queue and destroy superblock counters before delayed inode work decrements them. A local or container user must race writeback switching with cgroup or mount teardown; success triggers stale kernel-memory access that can crash the host or corrupt kernel state.

CVSS severity7.8
High
EPSS probability0.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux Kernel writeback allows local users to crash or compromise the host during container filesystem unmount. The gap after inode_prepare_wbs_switch() and before wb_queue_isw() lets unmount drain an empty queue and destroy superblock counters before delayed inode work decrements them. A local or container user must race writeback switching with cgroup or mount teardown; success triggers stale kernel-memory access that can crash the host or corrupt kernel state.

The record

CVE
CVE-2026-64378
Published
Jul 25, 2026
Updated
Jul 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.4.5 <4.5
  2. Affected versionversion=4.5
  3. Affected versionversion=a1a0e23e49037c23ea84bc8cc146a03584d13577 <087d5b8b501c570f84bf655164e6698c3ce146e0
  4. Affected versionversion=a1a0e23e49037c23ea84bc8cc146a03584d13577 <3c9c9648f77e4d14e50676bc51c2174ba9c8d361
  5. Affected versionversion=a1a0e23e49037c23ea84bc8cc146a03584d13577 <53eeaf4d63068dbc7708b0c7adb20151c812feca
  6. Affected versionversion=a1a0e23e49037c23ea84bc8cc146a03584d13577 <5c3265f3252b2ee50707adaaa3f9bd0df3df72de
  7. Affected versionversion=a1a0e23e49037c23ea84bc8cc146a03584d13577 <685fc15a410885b6d4dee64de0dce721b9428b12
  8. Affected versionversion=a1a0e23e49037c23ea84bc8cc146a03584d13577 <c923cc3cb5cd8945ceaf08252754110643446593
  9. Affected versionversion=a1a0e23e49037c23ea84bc8cc146a03584d13577 <cba38ec4cbd3a7b8b942a8d52531a05be8a9ff0d
  10. Affected versionversion=c5cbbec54fe71c4de2d34f8c0ec8fbfdd7f17339

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=4.4.5 <4.5; version=4.5; version=a1a0e23e49037c23ea84bc8cc146a03584d13577 <087d5b8b501c570f84bf655164e6698c3ce146e0; version=a1a0e23e49037c23ea84bc8cc146a03584d13577 <3c9c9648f77e4d14e50676bc51c2174ba9c8d361; version=a1a0e23e49037c23ea84bc8cc146a03584d13577 <53eeaf4d63068dbc7708b0c7adb20151c812feca; version=a1a0e23e49037c23ea84bc8cc146a03584d13577 <5c3265f3252b2ee50707adaaa3f9bd0df3df72de; version=a1a0e23e49037c23ea84bc8cc146a03584d13577 <685fc15a410885b6d4dee64de0dce721b9428b12; version=a1a0e23e49037c23ea84bc8cc146a03584d13577 <c923cc3cb5cd8945ceaf08252754110643446593; version=a1a0e23e49037c23ea84bc8cc146a03584d13577 <cba38ec4cbd3a7b8b942a8d52531a05be8a9ff0d; version=c5cbbec54fe71c4de2d34f8c0ec8fbfdd7f17339

Published CVSS scores

7.8kernel.orgCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

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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