CVE-2026-64386Network attack vector

Kernel memory corruption via SMB replay double-free

Published Jul 25, 2026 · Updated Jul 25, 2026

Double-free in the SMB client in Linux Kernel allows remote attackers to corrupt kernel memory via crafted SMB replay responses. In query_info(), one replayable response path frees its buffer, then an SMB2_query_info_init() failure preserves stale response bookkeeping that frees the buffer again. A malicious SMB server must induce both error paths; no user interaction or prior privilege is required, and the duplicate free can crash the kernel or corrupt kernel memory.

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 SMB client in Linux Kernel allows remote attackers to corrupt kernel memory via crafted SMB replay responses. In query_info(), one replayable response path frees its buffer, then an SMB2_query_info_init() failure preserves stale response bookkeeping that frees the buffer again. A malicious SMB server must induce both error paths; no user interaction or prior privilege is required, and the duplicate free can crash the kernel or corrupt kernel memory.

The record

CVE
CVE-2026-64386
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 <100fb7c455fa86d248b8bd7bb9de757c192870b4
  2. Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <2a88561d66eb855813cf004a0abe648bbb17de5e
  3. Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <3c81dda84799f76b42aec598564316e2964440db
  4. Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <89234773e8348918111aa15f6922b58cf3843364
  5. Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <f1add4acb656f5a82806a1ab0e63fed3d8b1bfca
  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 <100fb7c455fa86d248b8bd7bb9de757c192870b4; version=4f1fffa2376922f3d1d506e49c0fd445b023a28e <2a88561d66eb855813cf004a0abe648bbb17de5e; version=4f1fffa2376922f3d1d506e49c0fd445b023a28e <3c81dda84799f76b42aec598564316e2964440db; version=4f1fffa2376922f3d1d506e49c0fd445b023a28e <89234773e8348918111aa15f6922b58cf3843364; version=4f1fffa2376922f3d1d506e49c0fd445b023a28e <f1add4acb656f5a82806a1ab0e63fed3d8b1bfca; version=6.6.32 <6.6.145; version=6.8

Published CVSS scores

9.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.1Amazon LinuxCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
7.0Oracle LinuxCVSS:3.1/AV:L/AC:H/PR:L/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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