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Review reviewHigh

CVE-2026-64448

Linux

In the Linux kernel, the following vulnerability has been resolved: smb: client: restrict implied bcc[0] exemption to responses without data area smb2_check_message() has a long-standing quirk that accepts a response whose calculated length is one byte larger than the bytes actually received ("server can return one byte more due to implied bcc[0]"). This was introduced to accommodate servers that omit the trailing bcc[0] overlap byte when no data area is present. However, the exemption is applied unconditionally, regardless of whether the command actually carries a data area (has_smb2_data_...

CVSS
8.2
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.25
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 8.2

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: smb: client: restrict implied bcc[0] exemption to responses without data area smb2_check_message() has a long-standing quirk that accepts a response whose calculated length is one byte larger than the bytes actually received ("server can return one byte more due to implied bcc[0]"). This was introduced to accommodate servers that omit the trailing bcc[0] overlap byte when no data area is present. However, the exemption is applied unconditionally, regardless of whether the command actually carries a data area (has_smb2_data_...

Affected product and versions

Product
Linux
Affected versions
>= 093b2bdad3221e3fae3c26d89387e7297a157664 < 8d0bbc78046d264bbf6a574ea6f9072258a43e35, >= 093b2bdad3221e3fae3c26d89387e7297a157664 < b6a381c01e2ac98a48e32ac0f2a45bbadd9e26b0, >= 093b2bdad3221e3fae3c26d89387e7297a157664 < 31c6312608c60b72a1feb99a5afb680645a3e8a3, >= 093b2bdad3221e3fae3c26d89387e7297a157664 < 573e502d14714d2947e22e7eff40ec20a6a44a42, >= 093b2bdad3221e3fae3c26d89387e7297a157664 < 419ec1b604d7fb60c10aec2dc062371f9fcd4940, >= 093b2bdad3221e3fae3c26d89387e7297a157664 < ceb875a375dedbf51c9425c1d13a2d7a8435c08c, >= 093b2bdad3221e3fae3c26d89387e7297a157664 < 6e9d10f62773b99bd927940fd9cbdfe7207e23ff, >= 093b2bdad3221e3fae3c26d89387e7297a157664 < 53b7c271f06be4dd5cfc8c6ef552a8355c891a7f, >= 3.6
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
CWE
Not available