{"api_version":"1","generated_at":"2026-10-20T12:29:13+00:00","cve":"CVE-2026-98684","urls":{"html":"https://cve.report/CVE-2026-98684","api":"https://cve.report/api/cve/CVE-2026-98684.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98684","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98684"},"summary":{"title":"smb: client: flush and commit data before querying allocated ranges","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: flush and commit data before querying allocated ranges\n\nThe mode 0 / FALLOC_FL_KEEP_SIZE fallocate emulation for small interior\nranges in smb3_simple_fallocate_range() issues\nFSCTL_QUERY_ALLOCATED_RANGES and zero-fills any sub-range the server\nreports as an unallocated hole, to force block allocation without\nchanging file contents.\n\nThis is unsafe against Windows servers.  Per the Win32 documentation,\nFSCTL_QUERY_ALLOCATED_RANGES only reports ranges that *may* contain\nnonzero data and is explicitly not coherent with recently written data:\n\n  \"a call to FSCTL_QUERY_ALLOCATED_RANGES [after writing to a network\n   file] would not necessarily return a correct list of allocated\n   regions.  To ensure coherency [...] flush the data to the file\"\n\nfsx (generic/363) reproduces the resulting corruption against Windows\nServer 2022: a range is written, an uncached read returns the data, yet\nthe next FSCTL_QUERY_ALLOCATED_RANGES on that range reports it as a whole\nhole, so the emulation overwrites live data with zeroes.  A network trace\nconfirmed the WRITE, the READ returning data and the query returning an\nempty range list within microseconds.  Samba does not exhibit this; its\nquery is coherent with the written data.\n\nWrite back the dirty pages, drain any outstanding I/O and issue an SMB2\nFLUSH to force the server to commit the data before querying the\nallocated ranges, so the query reflects the data actually present.\n\nWith this, generic/363 passes against both Windows Server 2022 and Samba\nover 100000 fsx operations.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-18 16:17:21","updated_at":"2026-10-19 10:19:32"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/aa994489bd835547c191827acc460192e147032d","name":"https://git.kernel.org/stable/c/aa994489bd835547c191827acc460192e147032d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f82242fe3109a3ef72f429540b5bdde08fbfb0e4","name":"https://git.kernel.org/stable/c/f82242fe3109a3ef72f429540b5bdde08fbfb0e4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/bf84e44ff0ed802778eafd7ecb623635379cb506","name":"https://git.kernel.org/stable/c/bf84e44ff0ed802778eafd7ecb623635379cb506","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98684","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98684","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 966a3cb7c7db786452a87afdc3b48858fc4d4d6b f82242fe3109a3ef72f429540b5bdde08fbfb0e4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 966a3cb7c7db786452a87afdc3b48858fc4d4d6b bf84e44ff0ed802778eafd7ecb623635379cb506 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 966a3cb7c7db786452a87afdc3b48858fc4d4d6b aa994489bd835547c191827acc460192e147032d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c406bb9ece6ef63721daab106f132ff4b4234e81 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2f9f4a2d0e6fcf0673ed51195e06e47abe966900 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5e397c943424de94879830e72c95f2679e297a76 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.10.50 5.11 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.12.17 5.13 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.13.2 5.14 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.14","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.14 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.56 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.10 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/smb/client/smb2ops.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"f82242fe3109a3ef72f429540b5bdde08fbfb0e4","status":"affected","version":"966a3cb7c7db786452a87afdc3b48858fc4d4d6b","versionType":"git"},{"lessThan":"bf84e44ff0ed802778eafd7ecb623635379cb506","status":"affected","version":"966a3cb7c7db786452a87afdc3b48858fc4d4d6b","versionType":"git"},{"lessThan":"aa994489bd835547c191827acc460192e147032d","status":"affected","version":"966a3cb7c7db786452a87afdc3b48858fc4d4d6b","versionType":"git"},{"status":"affected","version":"c406bb9ece6ef63721daab106f132ff4b4234e81","versionType":"git"},{"status":"affected","version":"2f9f4a2d0e6fcf0673ed51195e06e47abe966900","versionType":"git"},{"status":"affected","version":"5e397c943424de94879830e72c95f2679e297a76","versionType":"git"},{"lessThan":"5.11","status":"affected","version":"5.10.50","versionType":"semver"},{"lessThan":"5.13","status":"affected","version":"5.12.17","versionType":"semver"},{"lessThan":"5.14","status":"affected","version":"5.13.2","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/smb/client/smb2ops.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.14"},{"lessThan":"5.14","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.56","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.10","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.56","versionStartIncluding":"5.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.10","versionStartIncluding":"5.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"5.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10.50","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12.17","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13.2","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: flush and commit data before querying allocated ranges\n\nThe mode 0 / FALLOC_FL_KEEP_SIZE fallocate emulation for small interior\nranges in smb3_simple_fallocate_range() issues\nFSCTL_QUERY_ALLOCATED_RANGES and zero-fills any sub-range the server\nreports as an unallocated hole, to force block allocation without\nchanging file contents.\n\nThis is unsafe against Windows servers.  Per the Win32 documentation,\nFSCTL_QUERY_ALLOCATED_RANGES only reports ranges that *may* contain\nnonzero data and is explicitly not coherent with recently written data:\n\n  \"a call to FSCTL_QUERY_ALLOCATED_RANGES [after writing to a network\n   file] would not necessarily return a correct list of allocated\n   regions.  To ensure coherency [...] flush the data to the file\"\n\nfsx (generic/363) reproduces the resulting corruption against Windows\nServer 2022: a range is written, an uncached read returns the data, yet\nthe next FSCTL_QUERY_ALLOCATED_RANGES on that range reports it as a whole\nhole, so the emulation overwrites live data with zeroes.  A network trace\nconfirmed the WRITE, the READ returning data and the query returning an\nempty range list within microseconds.  Samba does not exhibit this; its\nquery is coherent with the written data.\n\nWrite back the dirty pages, drain any outstanding I/O and issue an SMB2\nFLUSH to force the server to commit the data before querying the\nallocated ranges, so the query reflects the data actually present.\n\nWith this, generic/363 passes against both Windows Server 2022 and Samba\nover 100000 fsx operations."}],"providerMetadata":{"dateUpdated":"2026-10-19T09:23:54.479Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/f82242fe3109a3ef72f429540b5bdde08fbfb0e4"},{"url":"https://git.kernel.org/stable/c/bf84e44ff0ed802778eafd7ecb623635379cb506"},{"url":"https://git.kernel.org/stable/c/aa994489bd835547c191827acc460192e147032d"}],"title":"smb: client: flush and commit data before querying allocated ranges","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98684","datePublished":"2026-10-18T15:45:52.828Z","dateReserved":"2026-09-25T10:25:14.364Z","dateUpdated":"2026-10-19T09:23:54.479Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-18 16:17:21","lastModifiedDate":"2026-10-19 10:19:32","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98684","Ordinal":"1","Title":"smb: client: flush and commit data before querying allocated ran","CVE":"CVE-2026-98684","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98684","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: flush and commit data before querying allocated ranges\n\nThe mode 0 / FALLOC_FL_KEEP_SIZE fallocate emulation for small interior\nranges in smb3_simple_fallocate_range() issues\nFSCTL_QUERY_ALLOCATED_RANGES and zero-fills any sub-range the server\nreports as an unallocated hole, to force block allocation without\nchanging file contents.\n\nThis is unsafe against Windows servers.  Per the Win32 documentation,\nFSCTL_QUERY_ALLOCATED_RANGES only reports ranges that *may* contain\nnonzero data and is explicitly not coherent with recently written data:\n\n  \"a call to FSCTL_QUERY_ALLOCATED_RANGES [after writing to a network\n   file] would not necessarily return a correct list of allocated\n   regions.  To ensure coherency [...] flush the data to the file\"\n\nfsx (generic/363) reproduces the resulting corruption against Windows\nServer 2022: a range is written, an uncached read returns the data, yet\nthe next FSCTL_QUERY_ALLOCATED_RANGES on that range reports it as a whole\nhole, so the emulation overwrites live data with zeroes.  A network trace\nconfirmed the WRITE, the READ returning data and the query returning an\nempty range list within microseconds.  Samba does not exhibit this; its\nquery is coherent with the written data.\n\nWrite back the dirty pages, drain any outstanding I/O and issue an SMB2\nFLUSH to force the server to commit the data before querying the\nallocated ranges, so the query reflects the data actually present.\n\nWith this, generic/363 passes against both Windows Server 2022 and Samba\nover 100000 fsx operations.","Type":"Description","Title":"smb: client: flush and commit data before querying allocated ran"}]}}}