CVE-2026-64448Network attack vector

Pre-auth kernel disclosure and crash via SMB response

Published Jul 25, 2026 · Updated Jul 25, 2026

An out-of-bounds read in the Linux Kernel SMB client allows remote attackers to disclose kernel memory or crash the host. smb2_check_message() accepts a one-byte length mismatch even when an SMB response has a data area, causing SPNEGO and NTLMSSP decoders to read past the receive buffer. A malicious or compromised SMB server can trigger the flaw before authentication during NEGOTIATE or SESSION_SETUP, including on an automatic reconnect; disclosure is limited to one byte, while hardened kernels can panic.

CVSS severity8.2
High
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

An out-of-bounds read in the Linux Kernel SMB client allows remote attackers to disclose kernel memory or crash the host. smb2_check_message() accepts a one-byte length mismatch even when an SMB response has a data area, causing SPNEGO and NTLMSSP decoders to read past the receive buffer. A malicious or compromised SMB server can trigger the flaw before authentication during NEGOTIATE or SESSION_SETUP, including on an automatic reconnect; disclosure is limited to one byte, while hardened kernels can panic.

The record

CVE
CVE-2026-64448
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=093b2bdad3221e3fae3c26d89387e7297a157664 <31c6312608c60b72a1feb99a5afb680645a3e8a3
  2. Affected versionversion=093b2bdad3221e3fae3c26d89387e7297a157664 <419ec1b604d7fb60c10aec2dc062371f9fcd4940
  3. Affected versionversion=093b2bdad3221e3fae3c26d89387e7297a157664 <53b7c271f06be4dd5cfc8c6ef552a8355c891a7f
  4. Affected versionversion=093b2bdad3221e3fae3c26d89387e7297a157664 <573e502d14714d2947e22e7eff40ec20a6a44a42
  5. Affected versionversion=093b2bdad3221e3fae3c26d89387e7297a157664 <6e9d10f62773b99bd927940fd9cbdfe7207e23ff
  6. Affected versionversion=093b2bdad3221e3fae3c26d89387e7297a157664 <8d0bbc78046d264bbf6a574ea6f9072258a43e35
  7. Affected versionversion=093b2bdad3221e3fae3c26d89387e7297a157664 <b6a381c01e2ac98a48e32ac0f2a45bbadd9e26b0
  8. Affected versionversion=093b2bdad3221e3fae3c26d89387e7297a157664 <ceb875a375dedbf51c9425c1d13a2d7a8435c08c
  9. Affected versionversion=3.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=093b2bdad3221e3fae3c26d89387e7297a157664 <31c6312608c60b72a1feb99a5afb680645a3e8a3; version=093b2bdad3221e3fae3c26d89387e7297a157664 <419ec1b604d7fb60c10aec2dc062371f9fcd4940; version=093b2bdad3221e3fae3c26d89387e7297a157664 <53b7c271f06be4dd5cfc8c6ef552a8355c891a7f; version=093b2bdad3221e3fae3c26d89387e7297a157664 <573e502d14714d2947e22e7eff40ec20a6a44a42; version=093b2bdad3221e3fae3c26d89387e7297a157664 <6e9d10f62773b99bd927940fd9cbdfe7207e23ff; version=093b2bdad3221e3fae3c26d89387e7297a157664 <8d0bbc78046d264bbf6a574ea6f9072258a43e35; version=093b2bdad3221e3fae3c26d89387e7297a157664 <b6a381c01e2ac98a48e32ac0f2a45bbadd9e26b0; version=093b2bdad3221e3fae3c26d89387e7297a157664 <ceb875a375dedbf51c9425c1d13a2d7a8435c08c; version=3.6

Published CVSS scores

8.2Linux kernel CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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

T1499.004Application or System Exploitation

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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