CVE-2026-64387Network attack vector

Kernel memory corruption via stale response replay

Published Jul 25, 2026 · Updated Jul 25, 2026

A double-free in the Linux Kernel SMB client allows remote attackers to corrupt kernel memory through a directory-query replay. During SMB2_query_directory replay, cleanup retains the prior response type after freeing its buffer and frees that buffer again if SMB2_query_directory_init() fails. Reachability requires a directory query to an attacker-controlled SMB server; the resulting corruption enables a kernel crash or code execution.

CVSS severity9.8
Critical
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A double-free in the Linux Kernel SMB client allows remote attackers to corrupt kernel memory through a directory-query replay. During SMB2_query_directory replay, cleanup retains the prior response type after freeing its buffer and frees that buffer again if SMB2_query_directory_init() fails. Reachability requires a directory query to an attacker-controlled SMB server; the resulting corruption enables a kernel crash or code execution.

The record

CVE
CVE-2026-64387
Published
Jul 25, 2026
Updated
Jul 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-1341, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=433042a91f9373241307725b52de573933ffedbf <3409aedf3c81a810243da94164f6621c9d205c98
  2. Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <00b0fa425941438b664950a8ee65dfba2def4336
  3. Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <1665f25b1dea30bf2d02e16245d203a944c9d994
  4. Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <3317a5d015fca976475aa71df224056777316fde
  5. Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <9647492b5e41954be59d5157eddbcd4cdc1656f7
  6. Affected versionversion=6.6.32 <6.6.145
  7. Affected versionversion=6.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=433042a91f9373241307725b52de573933ffedbf <3409aedf3c81a810243da94164f6621c9d205c98; version=4f1fffa2376922f3d1d506e49c0fd445b023a28e <00b0fa425941438b664950a8ee65dfba2def4336; version=4f1fffa2376922f3d1d506e49c0fd445b023a28e <1665f25b1dea30bf2d02e16245d203a944c9d994; version=4f1fffa2376922f3d1d506e49c0fd445b023a28e <3317a5d015fca976475aa71df224056777316fde; version=4f1fffa2376922f3d1d506e49c0fd445b023a28e <9647492b5e41954be59d5157eddbcd4cdc1656f7; version=6.6.32 <6.6.145; version=6.8

Published CVSS scores

7.0Red HatCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
9.8Linux kernel CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1341Multiple Releases of Same Resource or Handle
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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