Linux Kernel up to 6.6.157/6.12.110/6.18.52 ksmbd behavioral workflow

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
9.5	$5k-$25k	0.80-

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.6.157/6.12.110/6.18.52 and classified as very critical. The impacted element is an unknown function of the component ksmbd. Executing a manipulation can lead to behavioral workflow. The identification of this vulnerability is CVE-2026-98901. The attack may be launched remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as very critical was found in Linux Kernel up to 6.6.157/6.12.110/6.18.52. This vulnerability affects an unknown code of the component ksmbd. The manipulation with an unknown input leads to a behavioral workflow vulnerability. The CWE definition for the vulnerability is CWE-841. The product supports a session in which more than one behavior must be performed by an actor, but it does not properly ensure that the actor performs the behaviors in the required sequence. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix lease break and ack state handling Do not skip valid lease states containing WRITE_CACHING when breaking level-II/read leases for writes and truncates. Handle lease break acknowledgments according to the SMB2 rule that the acknowledged state must be a subset of the server's break target. Apply the acknowledged state directly and keep the break pending on failed ACKs.

The advisory is available at git.kernel.org. This vulnerability was named CVE-2026-98901 since 09/25/2026. The exploitation appears to be easy. The attack can be initiated remotely. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 10/23/2026).

Upgrading to version 6.6.158, 6.12.111 or 6.18.53 eliminates this vulnerability. Applying the patch 17699905a381621c1cee5b6528feb05acedc86a4/3251ea36df5eef58aa207fbee48849d89b922ea6/fba4653a0b4dc2f6d42600abe21fb326292f70ff/5015191096db311759fef98769270336cd8b1324 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-108857). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.6.157
• 6.12.110
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39
• 6.18.40
• 6.18.41
• 6.18.42
• 6.18.43
• 6.18.44
• 6.18.45
• 6.18.46
• 6.18.47
• 6.18.48
• 6.18.49
• 6.18.50
• 6.18.51
• 6.18.52

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: 9.9
VulDB Meta Temp Score: 9.5

VulDB Base Score: 9.9
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

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

Exploitinginfo

Class: Behavioral workflow
CWE: CWE-841 / CWE-840
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.158/6.12.111/6.18.53
Patch: 17699905a381621c1cee5b6528feb05acedc86a4/3251ea36df5eef58aa207fbee48849d89b922ea6/fba4653a0b4dc2f6d42600abe21fb326292f70ff/5015191096db311759fef98769270336cd8b1324

Timelineinfo

09/25/2026 CVE reserved
10/23/2026 +28 days Advisory disclosed
10/23/2026 +0 days VulDB entry created
10/23/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-98901 (🔒)
GCVE (CVE): GCVE-0-2026-98901
GCVE (VulDB): GCVE-100-425674
EUVD: 🔒

Entryinfo

Created: 10/23/2026 14:25
Updated: 10/23/2026 15:59
Changes: 10/23/2026 14:25 (58), 10/23/2026 15:59 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Discussion

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