CVE-2026-64386

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SMB Client Query Info Double-Free in Linux Kernel

Publication date: 2026-07-25

Last updated on: 2026-08-11

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix query_info() replay double-free A response-bearing attempt can return a replayable error and free its response buffer. If SMB2_query_info_init() fails before the next send, cleanup retains the previous buffer type and frees that response again. Reset response bookkeeping before each attempt to prevent the stale free.

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Meta Information

Published

2026-07-25

Last Modified

2026-08-11

Generated

2026-08-14

AI Q&A

2026-07-25

EPSS Evaluated

2026-08-13

NVD

CVE-2026-64386

EUVD

EUVD-2026-48930

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This is a double-free vulnerability in the Linux kernel's SMB client implementation. It occurs when a response-bearing error is freed, but cleanup code mistakenly frees a stale response buffer from a previous attempt. This happens because response bookkeeping isn't reset properly before each new attempt.

Detection Guidance

This vulnerability is specific to the Linux kernel's SMB client implementation and may not have direct detection commands. Monitor kernel logs for SMB-related errors or crashes, particularly after SMB operations. Check for kernel oops or panic messages related to smb or cifs modules.

Impact Analysis

This could lead to kernel memory corruption or crashes if exploited. For end users, it might cause system instability or denial-of-service conditions when accessing SMB network shares.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards as it is a low-level kernel issue in the SMB client component. Compliance impacts would depend on whether the vulnerability could lead to unauthorized data access or disclosure, which is not described in the provided context.

Mitigation Strategies

Update the Linux kernel to the latest patched version that includes the fix for this vulnerability. Avoid using SMB client operations until the update is applied. If immediate patching is not possible, consider disabling SMB client functionality temporarily.

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