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CVSS 9.8 · CRITICAL

CVE-2026-64387Double-free vulnerability in Linux kernel SMB client

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix query directory replay double-free A response-bearing attempt can return a replayable error and free its response buffer. If SMB2_query_directory_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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Analysis

A critical double-free vulnerability has been identified in the Linux kernel SMB client. An attacker-controlled SMB server could exploit this during directory query replays to cause memory corruption or potentially execute arbitrary code on the client system.

Relevant roles

LinuxCyberSecurityCloudDockerKubernetesBackend

Severity

Score: 9.8(CRITICAL)
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
AV: NETWORK
AC: LOW
PR: NONE
UI: NONE
S: UNCHANGED
C: HIGH
I: HIGH
A: HIGH

EPSS

Probability of exploitation (next 30 days): 0.0017 (0.2%)
Percentile: 6.4%
EPSS: 2026-07-26

Technical description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix query directory replay double-free A response-bearing attempt can return a replayable error and free its response buffer. If SMB2_query_directory_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.

Published: 7/25/2026, 10:17:22 AM
Last modified: 7/27/2026, 5:16:45 AM

References

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