Linux Kernel up to 6.16-rc2 ksmbd ksmbd_krb5_authenticate User null pointer dereference

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5.5	$0-$5k	0.00

Summaryinfo

A vulnerability labeled as critical has been found in Linux Kernel up to 6.1.141/6.6.94/6.12.34/6.15.3/6.16-rc2. Affected is the function ksmbd_krb5_authenticate of the component ksmbd. The manipulation of the argument User results in null pointer dereference. This vulnerability is known as CVE-2025-38191. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.1.141/6.6.94/6.12.34/6.15.3/6.16-rc2. Affected is the function ksmbd_krb5_authenticate of the component ksmbd. The manipulation of the argument user with an unknown input leads to a null pointer dereference vulnerability. CWE is classifying the issue as 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. This is going to have an impact on availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix null pointer dereference in destroy_previous_session If client set ->PreviousSessionId on kerberos session setup stage, NULL pointer dereference error will happen. Since sess->user is not set yet, It can pass the user argument as NULL to destroy_previous_session. sess->user will be set in ksmbd_krb5_authenticate(). So this patch move calling destroy_previous_session() after ksmbd_krb5_authenticate().

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2025-38191 since 04/16/2025. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 249177 (Debian dsa-5973 : affs-modules-6.1.0-37-4kc-malta-di - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.142, 6.6.95, 6.12.35, 6.15.4 or 6.16-rc3 eliminates this vulnerability. Applying the patch 281afc52e2961cd5dd8326ebc9c5bc40904c0468/0902625a24eea7fdc187faa5d97df244d159dd6e/1193486dffb7432a09f57f5d09049b4d4123538b/076f1adefb9837977af7ed233883842ddc446644/7ac5b66acafcc9292fb935d7e03790f2b8b2dc0e 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 (249177), EUVD (EUVD-2025-20065) and CERT Bund (WID-SEC-2025-1465). Once again VulDB remains the best source for vulnerability data.

Affected

• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• IBM QRadar SIEM
• SUSE openSUSE
• RESF Rocky Linux
• Dell Avamar
• Open Source Linux Kernel
• Dell NetWorker
• Dell Secure Connect Gateway

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.1.141
• 6.6.0
• 6.6.1
• 6.6.2
• 6.6.3
• 6.6.4
• 6.6.5
• 6.6.6
• 6.6.7
• 6.6.8
• 6.6.9
• 6.6.10
• 6.6.11
• 6.6.12
• 6.6.13
• 6.6.14
• 6.6.15
• 6.6.16
• 6.6.17
• 6.6.18
• 6.6.19
• 6.6.20
• 6.6.21
• 6.6.22
• 6.6.23
• 6.6.24
• 6.6.25
• 6.6.26
• 6.6.27
• 6.6.28
• 6.6.29
• 6.6.30
• 6.6.31
• 6.6.32
• 6.6.33
• 6.6.34
• 6.6.35
• 6.6.36
• 6.6.37
• 6.6.38
• 6.6.39
• 6.6.40
• 6.6.41
• 6.6.42
• 6.6.43
• 6.6.44
• 6.6.45
• 6.6.46
• 6.6.47
• 6.6.48
• 6.6.49
• 6.6.50
• 6.6.51
• 6.6.52
• 6.6.53
• 6.6.54
• 6.6.55
• 6.6.56
• 6.6.57
• 6.6.58
• 6.6.59
• 6.6.60
• 6.6.61
• 6.6.62
• 6.6.63
• 6.6.64
• 6.6.65
• 6.6.66
• 6.6.67
• 6.6.68
• 6.6.69
• 6.6.70
• 6.6.71
• 6.6.72
• 6.6.73
• 6.6.74
• 6.6.75
• 6.6.76
• 6.6.77
• 6.6.78
• 6.6.79
• 6.6.80
• 6.6.81
• 6.6.82
• 6.6.83
• 6.6.84
• 6.6.85
• 6.6.86
• 6.6.87
• 6.6.88
• 6.6.89
• 6.6.90
• 6.6.91
• 6.6.92
• 6.6.93
• 6.6.94
• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
• 6.12.9
• 6.12.10
• 6.12.11
• 6.12.12
• 6.12.13
• 6.12.14
• 6.12.15
• 6.12.16
• 6.12.17
• 6.12.18
• 6.12.19
• 6.12.20
• 6.12.21
• 6.12.22
• 6.12.23
• 6.12.24
• 6.12.25
• 6.12.26
• 6.12.27
• 6.12.28
• 6.12.29
• 6.12.30
• 6.12.31
• 6.12.32
• 6.12.33
• 6.12.34
• 6.15.0
• 6.15.1
• 6.15.2
• 6.15.3
• 6.16-rc1
• 6.16-rc2

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.6
VulDB Meta Temp Score: 5.5

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

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
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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: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 249177
Nessus Name: Debian dsa-5973 : affs-modules-6.1.0-37-4kc-malta-di - security update

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.142/6.6.95/6.12.35/6.15.4/6.16-rc3
Patch: 281afc52e2961cd5dd8326ebc9c5bc40904c0468/0902625a24eea7fdc187faa5d97df244d159dd6e/1193486dffb7432a09f57f5d09049b4d4123538b/076f1adefb9837977af7ed233883842ddc446644/7ac5b66acafcc9292fb935d7e03790f2b8b2dc0e

Timelineinfo

04/16/2025 CVE reserved
07/04/2025 +79 days Advisory disclosed
07/04/2025 +0 days VulDB entry created
12/19/2025 +168 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-38191 (🔒)
GCVE (CVE): GCVE-0-2025-38191
GCVE (VulDB): GCVE-100-314940
EUVD: 🔒
CERT Bund: WID-SEC-2025-1465 - Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service

Entryinfo

Created: 07/04/2025 16:25
Updated: 12/19/2025 05:40
Changes: 07/04/2025 16:25 (60), 07/04/2025 21:07 (1), 07/20/2025 17:39 (7), 08/09/2025 17:43 (1), 08/13/2025 22:05 (2), 08/25/2025 16:14 (1), 09/02/2025 12:50 (1), 09/11/2025 01:44 (1), 09/21/2025 01:32 (1), 11/02/2025 23:48 (1), 12/08/2025 05:43 (1), 12/19/2025 05:40 (10)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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