CVE-2025-40008

Kernel crash via unrounded shadow-memory address

Published Oct 20, 2025 · Updated Oct 20, 2025

Out-of-bounds read in Linux KMSAN allows local users to crash a KMSAN-enabled kernel via an unaligned buffer ending at a guard page. The loop in kmsan_internal_set_shadow_origin rounds the buffer address and size for origin tracking but reads each origin's shadow bytes from the original unrounded address, crossing into unmapped shadow memory. Reachability requires an x86_64 kernel built with CONFIG_KMSAN and execution of the affected memset path; upstream documentation states that KMSAN is not intended for production use.

CVSS severity5.5
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Linux KMSAN allows local users to crash a KMSAN-enabled kernel via an unaligned buffer ending at a guard page. The loop in kmsan_internal_set_shadow_origin rounds the buffer address and size for origin tracking but reads each origin's shadow bytes from the original unrounded address, crossing into unmapped shadow memory. Reachability requires an x86_64 kernel built with CONFIG_KMSAN and execution of the affected memset path; upstream documentation states that KMSAN is not intended for production use.

The record

CVE
CVE-2025-40008
Published
Oct 20, 2025
Updated
Oct 20, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 20, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 20, 2025Record 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=19e85d939001946671643f4c16e1de8c633a6ce0 <df1fa034c0fc229a63d01ffb20bb919b839cb576
  2. Affected versionversion=2ef3cec44c60ae171b287db7fc2aa341586d65ba <5855792c6bb9a825607845db3feaddaff0414ec3
  3. Affected versionversion=2ef3cec44c60ae171b287db7fc2aa341586d65ba <85e1ff61060a765d91ee62dc5606d4d547d9d105
  4. Affected versionversion=2ef3cec44c60ae171b287db7fc2aa341586d65ba <f84e48707051812289b6c2684d4df2daa9d3bfbc
  5. Affected versionversion=6.10
  6. Affected versionversion=9ff078f5bad8990091f1639347de5e02636e9536 <e6684ed39edc35401a3341f85b1ab50a6f89a45d
  7. Affected versionversion=abeede7011da6c88e83ed260b909c140b8c9c250

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=19e85d939001946671643f4c16e1de8c633a6ce0 <df1fa034c0fc229a63d01ffb20bb919b839cb576; version=2ef3cec44c60ae171b287db7fc2aa341586d65ba <5855792c6bb9a825607845db3feaddaff0414ec3; version=2ef3cec44c60ae171b287db7fc2aa341586d65ba <85e1ff61060a765d91ee62dc5606d4d547d9d105; version=2ef3cec44c60ae171b287db7fc2aa341586d65ba <f84e48707051812289b6c2684d4df2daa9d3bfbc; version=6.10; version=9ff078f5bad8990091f1639347de5e02636e9536 <e6684ed39edc35401a3341f85b1ab50a6f89a45d; version=abeede7011da6c88e83ed260b909c140b8c9c250

Published CVSS scores

5.5Red HatCVSS: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.

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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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

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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