Linux Kernel up to 6.1.157/6.6.114/6.12.55/6.17.5 ksmbd handle_response null pointer dereference

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CTI Interest Score
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5.5$0-$5k0.00

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.1.157/6.6.114/6.12.55/6.17.5. This issue affects the function handle_response of the component ksmbd. Executing a manipulation can lead to null pointer dereference. This vulnerability is registered as CVE-2025-40084. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.1.157/6.6.114/6.12.55/6.17.5. This vulnerability affects the function handle_response of the component ksmbd. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: ksmbd: transport_ipc: validate payload size before reading handle handle_response() dereferences the payload as a 4-byte handle without verifying that the declared payload size is at least 4 bytes. A malformed or truncated message from ksmbd.mountd can lead to a 4-byte read past the declared payload size. Validate the size before dereferencing. This is a minimal fix to guard the initial handle read.

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2025-40084 since 04/16/2025. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 271980 (Linux Distros Unpatched Vulnerability : CVE-2025-40084), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.158, 6.6.115, 6.12.56 or 6.17.6 eliminates this vulnerability. Applying the patch a02e432d5130da4c723aabe1205bac805889fdb2/2dc125f5da134c0915a840b62565c60a595673dd/898d527ed94c19980a4d848f10057f1fed578ffb/867ffd9d67285612da3f0498ca618297f8e41f01 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (271980), EUVD (EUVD-2025-36664) and CERT Bund (WID-SEC-2025-2441). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • Open Source Linux Kernel
  • Dell NetWorker

Productinfo

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Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.7
VulDB Meta Temp Score: 5.5

VulDB Base Score: 5.7
VulDB Temp Score: 5.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 271980
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-40084

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.158/6.6.115/6.12.56/6.17.6
Patch: a02e432d5130da4c723aabe1205bac805889fdb2/2dc125f5da134c0915a840b62565c60a595673dd/898d527ed94c19980a4d848f10057f1fed578ffb/867ffd9d67285612da3f0498ca618297f8e41f01

Timelineinfo

04/16/2025 CVE reserved
10/29/2025 +196 days Advisory disclosed
10/29/2025 +0 days VulDB entry created
02/12/2026 +106 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-40084 (🔒)
GCVE (CVE): GCVE-0-2025-40084
GCVE (VulDB): GCVE-100-330400
EUVD: 🔒
CERT Bund: WID-SEC-2025-2441 - Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service

Entryinfo

Created: 10/29/2025 15:43
Updated: 02/12/2026 14:22
Changes: 10/29/2025 15:43 (59), 10/30/2025 12:31 (2), 11/03/2025 05:24 (1), 12/21/2025 23:48 (7), 01/07/2026 05:08 (1), 02/12/2026 14:22 (1)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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