CVE-2025-40084

Kernel-data disclosure and crash via undersized IPC payload

Published Oct 29, 2025 · Updated Oct 29, 2025

Out-of-bounds read in the Linux ksmbd IPC transport allows local users to disclose kernel data or crash the host via Generic Netlink. handle_response() treats an undersized response payload as a four-byte handle before checking its declared length, admitting later reads beyond the allocation. Reachability requires ksmbd to be running and a local Generic Netlink sender; builds enforcing CONFIG_SMB_SERVER_CHECK_CAP_NET_ADMIN also require CAP_NET_ADMIN.

CVSS severity7.1
High
EPSS probability0.14%
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 the Linux ksmbd IPC transport allows local users to disclose kernel data or crash the host via Generic Netlink. handle_response() treats an undersized response payload as a four-byte handle before checking its declared length, admitting later reads beyond the allocation. Reachability requires ksmbd to be running and a local Generic Netlink sender; builds enforcing CONFIG_SMB_SERVER_CHECK_CAP_NET_ADMIN also require CAP_NET_ADMIN.

The record

CVE
CVE-2025-40084
Published
Oct 29, 2025
Updated
Oct 29, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 29, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 29, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2dc125f5da134c0915a840b62565c60a595673dd
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <867ffd9d67285612da3f0498ca618297f8e41f01
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <898d527ed94c19980a4d848f10057f1fed578ffb
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a02e432d5130da4c723aabe1205bac805889fdb2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2dc125f5da134c0915a840b62565c60a595673dd; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <867ffd9d67285612da3f0498ca618297f8e41f01; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <898d527ed94c19980a4d848f10057f1fed578ffb; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a02e432d5130da4c723aabe1205bac805889fdb2

Published CVSS scores

7.1kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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.

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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