Linux Kernel up to 6.12.112/6.18.55/7.2.9/7.3-rc5 SMB Client smb3_zero_range buffer overflow

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.
5.3	$0-$5k	0.96+

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.12.112/6.18.55/7.2.9/7.3-rc5. It has been rated as critical. The affected element is the function smb3_zero_range of the component SMB Client. Performing a manipulation results in buffer overflow. This vulnerability is identified as CVE-2026-98686. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.12.112/6.18.55/7.2.9/7.3-rc5. This affects the function smb3_zero_range of the component SMB Client. The manipulation with an unknown input leads to a buffer overflow vulnerability. CWE is classifying the issue as CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: smb: client: discard post-EOF pagecache when extending a file via zero range smb3_zero_range() removed the pagecache only for the range being zeroed, so when it extends the file the folio straddling the old EOF - which may hold data dirtied past EOF through an mmap - was never dropped and became visible as file content once the file was extended. Lower the discard boundary to the smaller of the zero-range offset and the old EOF.

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-98686 since 09/25/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/18/2026).

Upgrading to version 6.12.113, 6.18.56, 7.2.10 or 7.3-rc6 eliminates this vulnerability. Applying the patch 94949b6b2f2bf0dba2e8786aed0b08cc6bc3a183/b75dadb50a25eed525264bf6fea44fad94e7626f/6a8279c98ad289b27c0bdb11adb3f0c0b7fd456d/da4fe97fb6c730d9c94a115c7bfa6f98e0d578d0 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.12.112
• 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
• 6.18.53
• 6.18.54
• 6.18.55
• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5
• 7.2.6
• 7.2.7
• 7.2.8
• 7.2.9
• 7.3-rc1
• 7.3-rc2
• 7.3-rc3
• 7.3-rc4
• 7.3-rc5

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: 5.5
VulDB Meta Temp Score: 5.3

VulDB Base Score: 5.5
VulDB Temp Score: 5.3
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: Buffer overflow
CWE: CWE-120 / CWE-119
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 6.12.113/6.18.56/7.2.10/7.3-rc6
Patch: 94949b6b2f2bf0dba2e8786aed0b08cc6bc3a183/b75dadb50a25eed525264bf6fea44fad94e7626f/6a8279c98ad289b27c0bdb11adb3f0c0b7fd456d/da4fe97fb6c730d9c94a115c7bfa6f98e0d578d0

Timelineinfo

09/25/2026 CVE reserved
10/18/2026 +23 days Advisory disclosed
10/18/2026 +0 days VulDB entry created
10/18/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-98686 (🔒)
GCVE (CVE): GCVE-0-2026-98686
GCVE (VulDB): GCVE-100-421911

Entryinfo

Created: 10/18/2026 19:12
Changes: 10/18/2026 19:12 (59)
Complete: 🔍
Cache ID: 216::103

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Discussion

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