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Review reviewHigh

CVE-2026-64395

Linux

In the Linux kernel, the following vulnerability has been resolved: ksmbd: require source read access for duplicate extents FSCTL_DUPLICATE_EXTENTS_TO_FILE passes the source file directly to vfs_clone_file_range() or vfs_copy_file_range() without checking the SMB access mask granted to the source handle. A handle opened with attribute access can consequently be used to copy file contents into an attacker-readable destination. Require FILE_READ_DATA on the source handle before either VFS operation, matching other ksmbd data-copy paths.

CVSS
7.5
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 7.5

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: ksmbd: require source read access for duplicate extents FSCTL_DUPLICATE_EXTENTS_TO_FILE passes the source file directly to vfs_clone_file_range() or vfs_copy_file_range() without checking the SMB access mask granted to the source handle. A handle opened with attribute access can consequently be used to copy file contents into an attacker-readable destination. Require FILE_READ_DATA on the source handle before either VFS operation, matching other ksmbd data-copy paths.

Affected product and versions

Product
Linux
Affected versions
>= eb817368f50c1cbe1bd07044124aad7db6330e3a < 2d2ab6983620c2d60ce7db72133984ca3873b929, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < 67bdad9cf01b25030e3bf00bbce6c309319d6663, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < b0d4d5cb846a1ddb7aaab9adfb5986e4540e6e5f, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < db231af842868268839f9f9619c68cb27830d8be, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < a10942af27832c2761d020863a46e79bebe0567d, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < cedff600f1642aa982178503552f0d007bc829c8, >= 5.15
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:H/I:N/A:N
CWE
Not available