{"api_version":"1","generated_at":"2026-09-18T02:28:43+00:00","cve":"CVE-2026-92487","urls":{"html":"https://cve.report/CVE-2026-92487","api":"https://cve.report/api/cve/CVE-2026-92487.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-92487","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-92487"},"summary":{"title":"exfat: fix valid_size extension over a shared writable mapping","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nexfat: fix valid_size extension over a shared writable mapping\n\nWhen a shared writable mapping has its valid_size extended by a buffered\nwrite or a page fault, exfat zeroes the page-cache gap below the new\nvalid_size. A store through the mapping can race with this zeroing and be\noverwritten.\n\nFix this by zeroing the gap lazily. Drop ->map_pages so that every first\nwrite fault goes through exfat_page_mkwrite(), which advances valid_size to\ncover the faulting page. With fault-around enabled, a store could install a\nwritable PTE, skip ->page_mkwrite(), and land past valid_size without\nadvancing it. Extending valid_size one faulting page at a time also leaves\nnever-written pages in a large mapping alone.\n\nThe gap is filled with block granularity, zeroing only the not-uptodate\nblocks and preserving blocks that may hold data stored through the mapping.\nOn the buffered-write path the invalidate lock is held and the gap is\nunmapped before zeroing, so a racing store re-faults and, under the inode\nlock, completes only after the gap has been zeroed and valid_size covers\nit.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-17 17:17:50","updated_at":"2026-09-17 17:17:50"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/24f20986b253c3e4eb13ebe3c2007d1d352408a6","name":"https://git.kernel.org/stable/c/24f20986b253c3e4eb13ebe3c2007d1d352408a6","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1135704ed22f54873eb0498a232611d9eca30dd4","name":"https://git.kernel.org/stable/c/1135704ed22f54873eb0498a232611d9eca30dd4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-92487","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-92487","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 82a81a7352bcf5f2756ac33d47ee0582737e9a85 24f20986b253c3e4eb13ebe3c2007d1d352408a6 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 82a81a7352bcf5f2756ac33d47ee0582737e9a85 1135704ed22f54873eb0498a232611d9eca30dd4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.2","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.6 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * 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/exfat/exfat_fs.h","fs/exfat/file.c","fs/exfat/iomap.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"24f20986b253c3e4eb13ebe3c2007d1d352408a6","status":"affected","version":"82a81a7352bcf5f2756ac33d47ee0582737e9a85","versionType":"git"},{"lessThan":"1135704ed22f54873eb0498a232611d9eca30dd4","status":"affected","version":"82a81a7352bcf5f2756ac33d47ee0582737e9a85","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/exfat/exfat_fs.h","fs/exfat/file.c","fs/exfat/iomap.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"7.2"},{"lessThan":"7.2","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.6","versionStartIncluding":"7.2","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"7.2","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nexfat: fix valid_size extension over a shared writable mapping\n\nWhen a shared writable mapping has its valid_size extended by a buffered\nwrite or a page fault, exfat zeroes the page-cache gap below the new\nvalid_size. A store through the mapping can race with this zeroing and be\noverwritten.\n\nFix this by zeroing the gap lazily. Drop ->map_pages so that every first\nwrite fault goes through exfat_page_mkwrite(), which advances valid_size to\ncover the faulting page. With fault-around enabled, a store could install a\nwritable PTE, skip ->page_mkwrite(), and land past valid_size without\nadvancing it. Extending valid_size one faulting page at a time also leaves\nnever-written pages in a large mapping alone.\n\nThe gap is filled with block granularity, zeroing only the not-uptodate\nblocks and preserving blocks that may hold data stored through the mapping.\nOn the buffered-write path the invalidate lock is held and the gap is\nunmapped before zeroing, so a racing store re-faults and, under the inode\nlock, completes only after the gap has been zeroed and valid_size covers\nit."}],"providerMetadata":{"dateUpdated":"2026-09-17T16:10:02.317Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/24f20986b253c3e4eb13ebe3c2007d1d352408a6"},{"url":"https://git.kernel.org/stable/c/1135704ed22f54873eb0498a232611d9eca30dd4"}],"title":"exfat: fix valid_size extension over a shared writable mapping","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-92487","datePublished":"2026-09-17T16:10:02.317Z","dateReserved":"2026-09-16T12:21:13.870Z","dateUpdated":"2026-09-17T16:10:02.317Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-17 17:17:50","lastModifiedDate":"2026-09-17 17:17:50","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"92487","Ordinal":"1","Title":"exfat: fix valid_size extension over a shared writable mapping","CVE":"CVE-2026-92487","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"92487","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nexfat: fix valid_size extension over a shared writable mapping\n\nWhen a shared writable mapping has its valid_size extended by a buffered\nwrite or a page fault, exfat zeroes the page-cache gap below the new\nvalid_size. A store through the mapping can race with this zeroing and be\noverwritten.\n\nFix this by zeroing the gap lazily. Drop ->map_pages so that every first\nwrite fault goes through exfat_page_mkwrite(), which advances valid_size to\ncover the faulting page. With fault-around enabled, a store could install a\nwritable PTE, skip ->page_mkwrite(), and land past valid_size without\nadvancing it. Extending valid_size one faulting page at a time also leaves\nnever-written pages in a large mapping alone.\n\nThe gap is filled with block granularity, zeroing only the not-uptodate\nblocks and preserving blocks that may hold data stored through the mapping.\nOn the buffered-write path the invalidate lock is held and the gap is\nunmapped before zeroing, so a racing store re-faults and, under the inode\nlock, completes only after the gap has been zeroed and valid_size covers\nit.","Type":"Description","Title":"exfat: fix valid_size extension over a shared writable mapping"}]}}}