CVE-2025-68817Network attack vector

Kernel memory corruption via tree-disconnect refcount race

Published Jan 13, 2026 · Updated Jan 13, 2026

Use-after-free in Linux Kernel ksmbd allows remote attackers to access freed kernel memory through concurrent SMB tree disconnects. The disconnect path waited for the tree-connection reference count to reach zero and then freed the object while the last ksmbd_tree_connect_put caller could still use it. Reachability requires an active ksmbd server and concurrent tree-scoped requests against a valid SMB session; guest shares can remove the credential gate.

CVSS severity9.8
Critical
EPSS probability0.45%
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 attackers to access freed kernel memory through concurrent SMB tree disconnects. The disconnect path waited for the tree-connection reference count to reach zero and then freed the object while the last ksmbd_tree_connect_put caller could still use it. Reachability requires an active ksmbd server and concurrent tree-scoped requests against a valid SMB session; guest shares can remove the credential gate.

The record

CVE
CVE-2025-68817
Published
Jan 13, 2026
Updated
Jan 13, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 13, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <063cbbc6f595ea36ad146e1b7d2af820894beb21
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <21a3d01fc6db5129f81edb0ab7cb94fd758bcbea
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b39a1833cc4a2755b02603eec3a71a85e9dff926
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d092de8a26c952379ded8e6b0bda31d89befac1a
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d64977495e44855f2b28d8ce56107c963a7a50e4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <063cbbc6f595ea36ad146e1b7d2af820894beb21; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <21a3d01fc6db5129f81edb0ab7cb94fd758bcbea; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b39a1833cc4a2755b02603eec3a71a85e9dff926; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d092de8a26c952379ded8e6b0bda31d89befac1a; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d64977495e44855f2b28d8ce56107c963a7a50e4

Published CVSS scores

9.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.8NIST NVDCVSS: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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1210Exploitation of Remote Services

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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