CVE-2025-38523Network attack vector

Kernel crash via unmarked slab usercopy region

Published Aug 16, 2025 · Updated Aug 5, 2026

Denial of service in Linux kernel 6.12 allows remote attackers to crash affected systems via crafted SMB Direct response data. The CIFS smbdirect receive path passes the smbd_response packet trailer to copy_to_iter(), but the slab does not mark that region for usercopy. Triggering the kernel BUG requires CONFIG_HARDENED_USERCOPY and an SMB Direct CIFS mount, whose creation requires CAP_SYS_ADMIN; the result is a service-interrupting kernel crash.

CVSS severity7.5
High
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux kernel 6.12 allows remote attackers to crash affected systems via crafted SMB Direct response data. The CIFS smbdirect receive path passes the smbd_response packet trailer to copy_to_iter(), but the slab does not mark that region for usercopy. Triggering the kernel BUG requires CONFIG_HARDENED_USERCOPY and an SMB Direct CIFS mount, whose creation requires CAP_SYS_ADMIN; the result is a service-interrupting kernel crash.

The record

CVE
CVE-2025-38523
Published
Aug 16, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-1188, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 16, 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

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=6.12
  2. Affected versionversion=ee4cdf7ba857a894ad1650d6ab77669cbbfa329e <43e7e284fc77b710d899569360ea46fa3374ae22
  3. Affected versionversion=ee4cdf7ba857a894ad1650d6ab77669cbbfa329e <87dcc7e33fc3dcb8ed32333cec016528b5bb6ce4
  4. Affected versionversion=ee4cdf7ba857a894ad1650d6ab77669cbbfa329e <f0dd353d47f7051afa98c6c60c7486831eb1a410

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.12; version=ee4cdf7ba857a894ad1650d6ab77669cbbfa329e <43e7e284fc77b710d899569360ea46fa3374ae22; version=ee4cdf7ba857a894ad1650d6ab77669cbbfa329e <87dcc7e33fc3dcb8ed32333cec016528b5bb6ce4; version=ee4cdf7ba857a894ad1650d6ab77669cbbfa329e <f0dd353d47f7051afa98c6c60c7486831eb1a410

Published CVSS scores

7.5LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.5CanonicalCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1188Initialization of a Resource with an Insecure Default
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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