CVE-2026-64257
Received Received - Intake

SMB2 Client Data Overlap Handling Flaw in Linux Kernel

Publication date: 2026-07-25

Last updated on: 2026-07-25

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: smb: client: reject overlapping data areas in SMB2 responses Commit 53b7c271f06b ("smb: client: restrict implied bcc[0] exemption to responses without data area") restricted the implied bcc[0] length exception to responses without a data area. However, the overlap handling in __smb2_calc_size() clears data_length, which can make an invalid response appear to have no data area and so qualify for the exception. Track data area overlap separately and reject such responses before applying the length compatibility exceptions.

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Meta Information

Published
2026-07-25
Last Modified
2026-07-25
Generated
2026-07-25
AI Q&A
2026-07-25
EPSS Evaluated
N/A
NVD
CVE-2026-64257
EUVD
EUVD-2026-48969

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a flaw in the SMB2 protocol client implementation. It allows an attacker to craft malicious SMB2 responses that bypass security checks by exploiting an overlap in data areas. The issue arises because the kernel incorrectly clears data length information, making invalid responses appear valid.

Impact Analysis

This vulnerability could allow an attacker to send specially crafted SMB2 responses to a vulnerable system, potentially leading to unauthorized access, data corruption, or denial of service. Systems using the Linux kernel with SMB2 client functionality are at risk.

Mitigation Strategies

Update the Linux kernel to a version that includes the fix for this vulnerability. Monitor vendor advisories for kernel updates and apply them promptly.

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