{"api_version":"1","generated_at":"2026-10-27T07:58:25+00:00","cve":"CVE-2026-72366","urls":{"html":"https://cve.report/CVE-2026-72366","api":"https://cve.report/api/cve/CVE-2026-72366.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-72366","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-72366"},"summary":{"title":"netfs: Fix netfs_create_write_req() to handle async cache object creation","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix netfs_create_write_req() to handle async cache object creation\n\nnetfs_create_write_req() will skip caching if the fscache cookie is\ndisabled, but this is a problem because async cache object creation might\nnot have got far enough yet that has been enabled - thereby causing the\ncall to fscache_begin_write_operation() to be skipped.\n\nFix this by removing the checks on the cookie and delegating this 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the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix netfs_create_write_req() to handle async cache object creation\n\nnetfs_create_write_req() will skip caching if the fscache cookie is\ndisabled, but this is a problem because async cache object creation might\nnot have got far enough yet that has been enabled - thereby causing the\ncall to fscache_begin_write_operation() to be skipped.\n\nFix this by removing the checks on the cookie and delegating this to\nfscache_begin_write_operation()."}],"metrics":[{"cvssV3_1":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:N - The bug is in netfs client write/cache coordination for CIFS, NFS+fscache, Ceph, AFS, and 9p. A malicious remote filesystem server can deliver file data and control protocol timing to drive async fscache object creation and subsequent kernel writeback over the network.\nAC:L - The attacker controls both sides of the race by interleaving reads and writes or triggering writeback while the fscache cookie is still in CREATING/LOOKING_UP; the async-creation window can be hit reliably with retries, not conditions outside attacker influence.\nPR:N - A malicious NFS/SMB/Ceph server needs no privileges on the victim client; once a fscache-enabled mount to that server exists, exploitation requires only ordinary file access or automated writeback, not real root or init-namespace capabilities.\nUI:N - After a triggering read from the remote server, kernel writeback can invoke netfs_writepages without further victim action; an attacker with file access can also drive the race directly through concurrent read/write syscalls.\nS:U - Impact is kernel heap/folio corruption during local pagecache I/O within the same kernel security authority; it does not inherently cross VM, container, IOMMU, or sandbox boundaries.\nC:H - Skipping fscache_begin_write_operation desynchronizes cache and writeback streams; the same netfs/fscache subsystem previously produced UAFs when PG_private_2 coordination failed, enabling disclosure via freed/reused folio memory.\nI:H - Inconsistent dual-stream write completion can free or reuse folios while still referenced, yielding heap corruption primitives that related netfs fscache bugs have leveraged for arbitrary kernel writes and privilege escalation.\nA:H - The related netfs fscache fix documented kernel oops, ceph caps warnings, RCU expedited stalls, and UAF crashes from this coordination failure class; skipping required cache setup can oops, panic, or hang the system during writeback."}]}],"providerMetadata":{"dateUpdated":"2026-10-21T12:44:41.841Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/aee03fbc8803a40d65e20f1af816a7219048a426"},{"url":"https://git.kernel.org/stable/c/8ab75e445c161c4cb504aa98e20ce1dd1ecd8e9a"},{"url":"https://git.kernel.org/stable/c/1188a9846fadeacf9d1430b528e5217f749d665b"},{"url":"https://git.kernel.org/stable/c/dbd6f56d975b23241b7bbb11bb8f562af548a0aa"}],"title":"netfs: Fix netfs_create_write_req() to handle async cache object creation","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-72366","datePublished":"2026-08-15T05:56:04.016Z","dateReserved":"2026-08-09T03:40:39.922Z","dateUpdated":"2026-10-21T12:44:41.841Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:22:10","lastModifiedDate":"2026-10-21 13:19:35","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"72366","Ordinal":"1","Title":"netfs: Fix netfs_create_write_req() to handle async cache object","CVE":"CVE-2026-72366","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"72366","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix netfs_create_write_req() to handle async cache object creation\n\nnetfs_create_write_req() will skip caching if the fscache cookie is\ndisabled, but this is a problem because async cache object creation might\nnot have got far enough yet that has been enabled - thereby causing the\ncall to fscache_begin_write_operation() to be skipped.\n\nFix this by removing the checks on the cookie and delegating this to\nfscache_begin_write_operation().","Type":"Description","Title":"netfs: Fix netfs_create_write_req() to handle async cache object"}]}}}