CVE-2026-64383Network attack vector

Kernel memory corruption via stale SMB response

Published Jul 25, 2026 · Updated Jul 25, 2026

Double-free in the Linux Kernel SMB client allows remote attackers to corrupt kernel memory through a malicious SMB server response. SMB2_flush retains response-buffer state across replay attempts, so flush_exit frees a stale response pointer again when a replayable response is followed by a failed retry. An SMB session and file handle must already exist; the server can then trigger a kernel oops or panic, expose kernel memory, or obtain write primitives.

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

Double-free in the Linux Kernel SMB client allows remote attackers to corrupt kernel memory through a malicious SMB server response. SMB2_flush retains response-buffer state across replay attempts, so flush_exit frees a stale response pointer again when a replayable response is followed by a failed retry. An SMB session and file handle must already exist; the server can then trigger a kernel oops or panic, expose kernel memory, or obtain write primitives.

The record

CVE
CVE-2026-64383
Published
Jul 25, 2026
Updated
Jul 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
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 <6e27f40b682a5e42a2daae3ce6d96f0e0e16dedb
  2. Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <013a9a3da46c5dabcf18f65ea6a47874ba12a15d
  3. Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <3407240cde132a4b72d6429a2625a09a2f78adaf
  4. Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <4be31c943a3a27a5a0251dbb8f5cb89059ec3d5a
  5. Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <878757163eea684750107a31ea134c103863515d
  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 <6e27f40b682a5e42a2daae3ce6d96f0e0e16dedb; version=4f1fffa2376922f3d1d506e49c0fd445b023a28e <013a9a3da46c5dabcf18f65ea6a47874ba12a15d; version=4f1fffa2376922f3d1d506e49c0fd445b023a28e <3407240cde132a4b72d6429a2625a09a2f78adaf; version=4f1fffa2376922f3d1d506e49c0fd445b023a28e <4be31c943a3a27a5a0251dbb8f5cb89059ec3d5a; version=4f1fffa2376922f3d1d506e49c0fd445b023a28e <878757163eea684750107a31ea134c103863515d; version=6.6.32 <6.6.145; version=6.8

Published CVSS scores

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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