CVE-2026-64399

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE<br /> <br /> The FSCTL_DUPLICATE_EXTENTS_TO_FILE arm of smb2_ioctl() overwrites the<br /> destination file&amp;#39;s data via vfs_clone_file_range() with neither the<br /> share-level KSMBD_TREE_CONN_FLAG_WRITABLE check nor a per-handle<br /> fp-&gt;daccess check that the other write-bearing arms carry. A client can<br /> overwrite destination data on a read-only share, or from a handle opened<br /> with only FILE_WRITE_ATTRIBUTES (which still yields an FMODE_WRITE filp).<br /> FILE_WRITE_ATTRIBUTES-only destination handle overwrote the file&amp;#39;s data via<br /> the clone. Add both checks, matching the FSCTL_SET_SPARSE permission fix;<br /> require FILE_WRITE_DATA since this writes data.