CVE-2026-64396Network attack vector

Kernel memory corruption via deferred-lock cancellation race

Published Jul 25, 2026 · Updated Jul 25, 2026

Use-after-free in Linux Kernel ksmbd allows remote authenticated users to corrupt kernel memory through crafted SMB2 lock cancellation. The FILE_LOCK_DEFERRED cleanup frees flock before removing its asynchronous work, letting concurrent smb2_cancel processing dereference the stale pointer. An ordinary SMB share user controlling conflicting handles and CLOSE/CANCEL sequencing can trigger a kernel oops or panic and attacker-influenced heap corruption.

CVSS severity8.8
High
EPSS probability0.43%
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 ksmbd allows remote authenticated users to corrupt kernel memory through crafted SMB2 lock cancellation. The FILE_LOCK_DEFERRED cleanup frees flock before removing its asynchronous work, letting concurrent smb2_cancel processing dereference the stale pointer. An ordinary SMB share user controlling conflicting handles and CLOSE/CANCEL sequencing can trigger a kernel oops or panic and attacker-influenced heap corruption.

The record

CVE
CVE-2026-64396
Published
Jul 25, 2026
Updated
Jul 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-825, T1210
Attack vector
network
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=0 <6.1.178
  2. Affected versionversion=0 <6.12.96
  3. Affected versionversion=0 <6.18.39
  4. Affected versionversion=0 <6.6.145
  5. Affected versionversion=0 <7.1.4
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <367c42a611fe488b7b03f1f6737f4dee0e8b20a2
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <463bbd79698513af4dad50fe1c573825f297ca2e
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5aa1cb01155f96824003baf7997cdf1f150caba3
  9. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5c75275c0fc9a2deb0d8f5604edcb16f288171c8
  10. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7703fd9aba1f2483c8e55f9ff73b7663e0761ed9
  11. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d20d1c8ba5765d1d12eefc0aee6385ab3f240e1e

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0 <6.1.178; version=0 <6.12.96; version=0 <6.18.39; version=0 <6.6.145; version=0 <7.1.4; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <367c42a611fe488b7b03f1f6737f4dee0e8b20a2; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <463bbd79698513af4dad50fe1c573825f297ca2e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5aa1cb01155f96824003baf7997cdf1f150caba3; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5c75275c0fc9a2deb0d8f5604edcb16f288171c8; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7703fd9aba1f2483c8e55f9ff73b7663e0761ed9; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d20d1c8ba5765d1d12eefc0aee6385ab3f240e1e

Published CVSS scores

8.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.5Amazon LinuxCVSS:3.1/AV:N/AC:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-825Expired Pointer Dereference
T1210Exploitation of Remote Services

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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