Linux Kernel up to 6.18.60/7.3.1 ksmbd get_file_stream_info 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.
9.5	$5k-$25k	1.18+

Summaryinfo

A vulnerability marked as very critical has been reported in Linux Kernel up to 6.18.60/7.3.1. The affected element is the function get_file_stream_info of the component ksmbd. This manipulation causes buffer overflow. This vulnerability is registered as CVE-2026-99273. Remote exploitation of the attack is possible. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.18.60/7.3.1 and classified as very critical. Affected by this vulnerability is the function get_file_stream_info of the component ksmbd. The manipulation with an unknown input leads to a buffer overflow vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: ksmbd: reserve space for the UTF-16 terminator in stream info smb_strtoUTF16() always writes a terminating zero UTF-16 unit after the converted characters, but get_file_stream_info() budgets only sizeof(struct smb2_file_stream_info) + streamlen * 2 for a stream entry and sizeof(struct smb2_file_stream_info) + 7 * 2 for the trailing "::$DATA" entry. When an entry exactly fills the 448-byte small response buffer, the terminator is written two bytes past the allocation. Reserve one extra UTF-16 unit in both budget checks. The terminator is not part of the wire format, so the reported lengths are unchanged.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-99273 since 09/25/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details are known, but no exploit is available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 11/07/2026).

Upgrading to version 6.18.61, 7.3.2 or 7.4-rc1 eliminates this vulnerability. Applying the patch 06a751809ebd33e95b05bf733697318a17a4872b/0e64f89563164719ceb1aa33f2a8bfd6391fa340/a025c4991a7d83edc4dd339e3ea86d8ff6226eca is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 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
• 6.18.56
• 6.18.57
• 6.18.58
• 6.18.59
• 6.18.60
• 7.3.0
• 7.3.1

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: 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 6.18.61/7.3.2/7.4-rc1
Patch: 06a751809ebd33e95b05bf733697318a17a4872b/0e64f89563164719ceb1aa33f2a8bfd6391fa340/a025c4991a7d83edc4dd339e3ea86d8ff6226eca

Timelineinfo

09/25/2026 CVE reserved
11/07/2026 +43 days Advisory disclosed
11/07/2026 +0 days VulDB entry created
11/07/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CNA: Linux
CVE: CVE-2026-99273 (🔒)

GCVE (CVE): GCVE-0-2026-99273
GCVE (VulDB): GCVE-100-432625

Entryinfo

Created: 11/07/2026 15:38
Changes: 11/07/2026 15:38 (59)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

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