{"id":"CVE-2026-53392","state":"PUBLISHED","title":"NFSv4/flexfiles: reject zero filehandle version count","description":"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->fh_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.","publishedAt":"2026-07-19T12:01:56.101Z","updatedAt":"2026-10-19T20:07:46.094Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"9033591535c066726f5b505126ccb4068b98fa4f","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"18cc6d57a14fa65ab2a2b52279f549041c4bc9cf","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"be7829715e341b42846437dd9e721005db59f0cc","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"eeabb9020721db6bc132e68eeae380b8d4fb4b04","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"7779c85028a0676fb190cde4f0c540f4f8e97761","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"d8c90c7cc061265d5f2813a1f5c82ef2f4707e67","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"2131ed64b767ffa8bcdb3677d90f3964e39aabc8","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/flexfilelayout/flexfilelayout.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.0","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.38","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.3","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/flexfilelayout/flexfilelayout.c"]}],"references":["https://git.kernel.org/stable/c/9033591535c066726f5b505126ccb4068b98fa4f","https://git.kernel.org/stable/c/18cc6d57a14fa65ab2a2b52279f549041c4bc9cf","https://git.kernel.org/stable/c/be7829715e341b42846437dd9e721005db59f0cc","https://git.kernel.org/stable/c/eeabb9020721db6bc132e68eeae380b8d4fb4b04","https://git.kernel.org/stable/c/7779c85028a0676fb190cde4f0c540f4f8e97761","https://git.kernel.org/stable/c/d8c90c7cc061265d5f2813a1f5c82ef2f4707e67","https://git.kernel.org/stable/c/2131ed64b767ffa8bcdb3677d90f3964e39aabc8","https://git.kernel.org/stable/c/2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2"],"weaknesses":["CWE-20"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/53xxx/CVE-2026-53392.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53392","state":"PUBLISHED","datePublished":"2026-07-19T12:01:56.101Z","dateUpdated":"2026-10-19T20:07:46.094Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-06-09T07:44:35.402Z"},"containers":{"cna":{"title":"NFSv4/flexfiles: reject zero filehandle version count","descriptions":[{"lang":"en","value":"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->fh_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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"9033591535c066726f5b505126ccb4068b98fa4f","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"18cc6d57a14fa65ab2a2b52279f549041c4bc9cf","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"be7829715e341b42846437dd9e721005db59f0cc","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"eeabb9020721db6bc132e68eeae380b8d4fb4b04","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"7779c85028a0676fb190cde4f0c540f4f8e97761","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"d8c90c7cc061265d5f2813a1f5c82ef2f4707e67","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"2131ed64b767ffa8bcdb3677d90f3964e39aabc8","versionType":"git"},{"version":"d67ae825a59d639e4d8b82413af84d854617a87e","status":"affected","lessThan":"2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/flexfilelayout/flexfilelayout.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.0","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.38","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.3","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/flexfilelayout/flexfilelayout.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/9033591535c066726f5b505126ccb4068b98fa4f"},{"url":"https://git.kernel.org/stable/c/18cc6d57a14fa65ab2a2b52279f549041c4bc9cf"},{"url":"https://git.kernel.org/stable/c/be7829715e341b42846437dd9e721005db59f0cc"},{"url":"https://git.kernel.org/stable/c/eeabb9020721db6bc132e68eeae380b8d4fb4b04"},{"url":"https://git.kernel.org/stable/c/7779c85028a0676fb190cde4f0c540f4f8e97761"},{"url":"https://git.kernel.org/stable/c/d8c90c7cc061265d5f2813a1f5c82ef2f4707e67"},{"url":"https://git.kernel.org/stable/c/2131ed64b767ffa8bcdb3677d90f3964e39aabc8"},{"url":"https://git.kernel.org/stable/c/2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The bug is in the NFSv4 pNFS flexfiles client parsing a malicious LAYOUTGET layout blob from the server over NFS/RPC; a remote attacker who controls or MITMs the NFS server delivers the crafted fh_count=0 response over the network.\nAC:L - Once a client is using flexfiles pNFS, the attacker fully controls the layout XDR and can set fh_count=0 to deterministically store ZERO_SIZE_PTR; a later I/O, layoutstats, or LAYOUTRETURN path dereferences fh_versions[0] and panics without races or special heap layout.\nPR:N - Exploitation requires no privileges on the victim host; the attacker only needs to be the (or impersonate) the NFS server sending protocol responses after normal client connection/authentication.\nUI:N - After an NFS pNFS flexfiles mount is established (common in enterprise/HPC NAS deployments), triggering the malformed layout and subsequent kernel panic requires no further victim action beyond routine file access on the already-mounted share.\nS:U - Impact is a kernel oops/panic on the NFS client host; it does not cross a VM, container, or IOMMU security boundary to affect a different authority.\nC:N - The failure mode is a NULL-pointer dereference at ZERO_SIZE_PTR (0x10) when accessing fh_versions[0]; KASAN confirms a faulting dereference with no successful out-of-bounds read or information leak to userspace.\nI:N - There is no memory corruption or successful write primitive—only an invalid-pointer dereference that crashes the kernel before any integrity-changing operation completes.\nA:H - A confirmed KASAN null-ptr-deref in ff_layout_encode_ff_layoutupdate during LAYOUTRETURN encoding causes a fatal kernel exception/panic, fully denying availability of the client system."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:50:43.747Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.0","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.0","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.0","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.0","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.0","versionEndExcluding":"6.12.96"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.0","versionEndExcluding":"6.18.38"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.0","versionEndExcluding":"7.1.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.0","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-53392","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:30:14.556570Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-20","lang":"en","type":"CWE","description":"CWE-20 Improper Input Validation"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:07:46.094Z"}}]}}}