{"id":"CVE-2026-53392","summary":"NFSv4/flexfiles: reject zero filehandle version count","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSv4/flexfiles: reject zero filehandle version count\n\nff_layout_alloc_lseg() decodes the filehandle-version array count\nfrom the flexfiles layout body. The value is used as the count for\nkzalloc_objs(), and the current code only rejects NULL.\n\nA zero count yields ZERO_SIZE_PTR, which can be stored in\ndss_info-\u003efh_versions even though later flexfiles paths assume that at\nleast one filehandle version exists.\n\nReject fh_count == 0 before the allocation, matching the existing zero\nversion_count validation in the flexfiles GETDEVICEINFO parser.\n\nA QEMU/KASAN run with a malformed flexfiles layout hit:\n\n  KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]\n  RIP: 0010:ff_layout_encode_ff_layoutupdate.isra.0+0x15f/0x750\n  ff_layout_encode_layoutreturn+0x683/0x970\n  nfs4_xdr_enc_layoutreturn+0x278/0x3a0\n  Kernel panic - not syncing: Fatal exception\n\nThe patched kernel rejects the malformed layout without KASAN/oops/panic,\nand a valid fh_count=1 regression still opens, reads, and unmounts cleanly.","modified":"2026-07-22T05:30:03.996066971Z","published":"2026-07-19T12:01:56.101Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53392.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2131ed64b767ffa8bcdb3677d90f3964e39aabc8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7779c85028a0676fb190cde4f0c540f4f8e97761"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d8c90c7cc061265d5f2813a1f5c82ef2f4707e67"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53392.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53392"},{"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":"d67ae825a59d639e4d8b82413af84d854617a87e"},{"fixed":"7779c85028a0676fb190cde4f0c540f4f8e97761"},{"fixed":"d8c90c7cc061265d5f2813a1f5c82ef2f4707e67"},{"fixed":"2131ed64b767ffa8bcdb3677d90f3964e39aabc8"},{"fixed":"2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53392.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.0.0"},{"fixed":"6.12.96"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.38"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.3"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53392.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:N/I:N/A:H"}]}