CVE-2025-40193

Kernel crash via unchecked simdisk write length

Published Nov 12, 2025 · Updated May 11, 2026

Improper input validation in Linux 3.9 through affected 6.x branches allows local users to crash the kernel via the Xtensa simdisk proc file. proc_write_simdisk passes an unchecked user-supplied write length to memdup_user_nul, allowing an invalid allocation request to reach kernel memory handling. The Xtensa ISS simdisk interface must be present and locally writable; the documented consequence is a host availability interruption.

CVSS severity6.8
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Linux 3.9 through affected 6.x branches allows local users to crash the kernel via the Xtensa simdisk proc file. proc_write_simdisk passes an unchecked user-supplied write length to memdup_user_nul, allowing an invalid allocation request to reach kernel memory handling. The Xtensa ISS simdisk interface must be present and locally writable; the documented consequence is a host availability interruption.

The record

CVE
CVE-2025-40193
Published
Nov 12, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 12, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=3.9
  2. Affected versionversion=b6c7e873daf765e41233b9752083b66442703b7a <151bd88859474cdaccc1e4c8b21fbf72dbba2ab4
  3. Affected versionversion=b6c7e873daf765e41233b9752083b66442703b7a <5d5f08fd0cd970184376bee07d59f635c8403f63
  4. Affected versionversion=b6c7e873daf765e41233b9752083b66442703b7a <a0c2c36d864ef3676b05cfd8c58b72ee3214cb1a
  5. Affected versionversion=b6c7e873daf765e41233b9752083b66442703b7a <d381de7fd4cdc928ede96987dc64b133e6480dd6
  6. Affected versionversion=b6c7e873daf765e41233b9752083b66442703b7a <f40405ccfb87b71175f2d5d004c0b8a0aebcc2cf

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.9; version=b6c7e873daf765e41233b9752083b66442703b7a <151bd88859474cdaccc1e4c8b21fbf72dbba2ab4; version=b6c7e873daf765e41233b9752083b66442703b7a <5d5f08fd0cd970184376bee07d59f635c8403f63; version=b6c7e873daf765e41233b9752083b66442703b7a <a0c2c36d864ef3676b05cfd8c58b72ee3214cb1a; version=b6c7e873daf765e41233b9752083b66442703b7a <d381de7fd4cdc928ede96987dc64b133e6480dd6; version=b6c7e873daf765e41233b9752083b66442703b7a <f40405ccfb87b71175f2d5d004c0b8a0aebcc2cf

Published CVSS scores

5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
6.8SUSECVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

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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