{"id":"CVE-2026-64399","summary":"ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE\n\nThe FSCTL_DUPLICATE_EXTENTS_TO_FILE arm of smb2_ioctl() overwrites the\ndestination file's data via vfs_clone_file_range() with neither the\nshare-level KSMBD_TREE_CONN_FLAG_WRITABLE check nor a per-handle\nfp-\u003edaccess check that the other write-bearing arms carry. A client can\noverwrite destination data on a read-only share, or from a handle opened\nwith only FILE_WRITE_ATTRIBUTES (which still yields an FMODE_WRITE filp).\nFILE_WRITE_ATTRIBUTES-only destination handle overwrote the file's data via\nthe clone. Add both checks, matching the FSCTL_SET_SPARSE permission fix;\nrequire FILE_WRITE_DATA since this writes data.","modified":"2026-07-28T04:03:00.930262547Z","published":"2026-07-25T08:50:42.925Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64399.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/388e4139db27a9e3612c9d356b826f5b1ff6a9e3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/620d133d469295ee7c017ca6aafac335f65c4a5a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9b9cf7e65cbeaae1b6636144bacee611cdd7a5d6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/baae7b39673ec21073a25e3d14f8feaada01d5df"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bf460ad5958d506492de4524a656439da3f99c51"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c917e4522d251071dde9871b9142d8ea1186ebfe"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64399.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64399"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"eb817368f50c1cbe1bd07044124aad7db6330e3a"},{"fixed":"bf460ad5958d506492de4524a656439da3f99c51"},{"fixed":"620d133d469295ee7c017ca6aafac335f65c4a5a"},{"fixed":"9b9cf7e65cbeaae1b6636144bacee611cdd7a5d6"},{"fixed":"baae7b39673ec21073a25e3d14f8feaada01d5df"},{"fixed":"c917e4522d251071dde9871b9142d8ea1186ebfe"},{"fixed":"388e4139db27a9e3612c9d356b826f5b1ff6a9e3"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64399.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.15.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.96"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.39"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64399.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}