CVE-2025-38561Network attack vector

Kernel code execution via Preauth_HashValue lifetime race

Published Aug 19, 2025 · Updated Aug 5, 2026

Race condition in Linux ksmbd allows remote attackers to execute kernel code via concurrent SMB2 SESSION_SETUP requests. smb2_sess_setup frees sess->Preauth_HashValue during session setup without proper synchronization, allowing parallel requests to reuse, double-free, and write through the freed kernel-heap object. The pre-authentication path is reachable on TCP port 445 when ksmbd is running; exploitation can disclose SMB session keys, corrupt kernel memory, or crash the host.

CVSS severity9.8
Critical
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

Race condition in Linux ksmbd allows remote attackers to execute kernel code via concurrent SMB2 SESSION_SETUP requests. smb2_sess_setup frees sess->Preauth_HashValue during session setup without proper synchronization, allowing parallel requests to reuse, double-free, and write through the freed kernel-heap object. The pre-authentication path is reachable on TCP port 445 when ksmbd is running; exploitation can disclose SMB session keys, corrupt kernel memory, or crash the host.

The record

CVE
CVE-2025-38561
Published
Aug 19, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-362, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=0626e6641f6b467447c81dd7678a69c66f7746cf <44a3059c4c8cc635a1fb2afd692d0730ca1ba4b6
  2. Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <6613887da1d18dd2ecfd6c6148a873c4d903ebdc
  3. Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <7d7c0c5304c88bcbd7a85e9bcd61d27e998ba5fc
  4. Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <b69fd87076daa66f3d186bd421a7b0ee0cb45829
  5. Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <edeecc7871e8fc0878d53ce286c75040a0e38f6c
  6. Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <fbf5c0845ed15122a770bca9be1d9b60b470d3aa
  7. Affected versionversion=5.15

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0626e6641f6b467447c81dd7678a69c66f7746cf <44a3059c4c8cc635a1fb2afd692d0730ca1ba4b6; version=0626e6641f6b467447c81dd7678a69c66f7746cf <6613887da1d18dd2ecfd6c6148a873c4d903ebdc; version=0626e6641f6b467447c81dd7678a69c66f7746cf <7d7c0c5304c88bcbd7a85e9bcd61d27e998ba5fc; version=0626e6641f6b467447c81dd7678a69c66f7746cf <b69fd87076daa66f3d186bd421a7b0ee0cb45829; version=0626e6641f6b467447c81dd7678a69c66f7746cf <edeecc7871e8fc0878d53ce286c75040a0e38f6c; version=0626e6641f6b467447c81dd7678a69c66f7746cf <fbf5c0845ed15122a770bca9be1d9b60b470d3aa; version=5.15

Published CVSS scores

8.5Zero Day InitiativeCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
9.8Linux CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.5CISA ADPCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1190Exploit Public-Facing Application

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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