{"api_version":"1","generated_at":"2026-10-26T11:08:33+00:00","cve":"CVE-2026-72315","urls":{"html":"https://cve.report/CVE-2026-72315","api":"https://cve.report/api/cve/CVE-2026-72315.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-72315","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-72315"},"summary":{"title":"smb: client: fix busy dentry warning on unmount after DIO","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix busy dentry warning on unmount after DIO\n\nCommit c68337442f03 (\"cifs: Fix busy dentry used after unmounting\") fixed\nthe issue in cifs where deferred close of a file led to a dentry reference\ncount not being released in umount, by flushing deferredclose_wq in\ncifs_kill_sb() to solve it.\n\nHowever, the cifs DIO path suffers from the same busy-dentry problem caused\nby a delayed dentry reference-count release:\n\n\t[dio]\t\t\t[cifsd]\t\t\t[close + umount]\nnetfs_unbuffered_write_iter_locked\n...\n\t\t\t\tcifs_demultiplex_thread\n netfs_unbuffered_write\n  cifs_issue_write\n  netfs_wait_for_in_progress_stream [1]\n\t\t\t\t...\n\t\t\t\t netfs_write_subrequest_terminated\n\t\t\t\t  netfs_subreq_clear_in_progress\n\t\t\t\t   netfs_wake_collector // wake [1]\n\t\t\t\t  netfs_put_subrequest\n netfs_put_request\n  queue_work(system_dfl_wq, xxx) [2]\n // dio write return\t\t\t\t\tcifs_close\n\t\t\t\t\t\t\t _cifsFileInfo_put\n\t\t\t\t\t\t\t  // cfile->count 2->1\n\t\t\t\t\t\t\t  --cfile->count [3]\n\n\t\t\t\t\t\t\t// umount\n\t\t\t\t\t\t\tcifs_kill_sb\n\t\t\t\t\t\t\t kill_anon_super\n\t\t\t\t\t\t\t  // warning triggered!\n\t\t\t\t\t\t\t  shrink_dcache_for_umount [4]\n[system_dfl_wq] [5]\nnetfs_free_request\n ...\n _cifsFileInfo_put\n  // cfile->count 1->0\n  --cfile->count\n  queue_work(fileinfo_put_wq, xxx)\n\n[fileinfo_put_wq] [6]\ncifsFileInfo_put_work\n cifsFileInfo_put_final\n  dput\n\nIf the umount path is triggered before [5], it results warning:\nBUG: Dentry 00000000eab1f070{i=9a917b66ae404fec,n=test}  still in use (1)\n[unmount of cifs cifs]\n\nThe existing per-inode ictx->io_count wait in cifs_evict_inode() does not\nhelp: it lives in the inode eviction path, which runs after\nshrink_dcache_for_umount() has already warned about the busy dentries.\n\nFix it by adding a per-superblock outstanding-rreq counter that is\nincremented in cifs_init_request() and decremented in cifs_free_request().\nIn cifs_kill_sb(), before kill_anon_super(), wait for this counter to reach\n0 - which guarantees that all cleanup_work for this sb have run and thus\nall relevant cfile puts are queued on fileinfo_put_wq or serverclose_wq.\nThen drain the workqueue so the dentry refs are dropped.\n\nThis is a targeted wait, not a flush of the system-wide system_dfl_wq.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 06:22:04","updated_at":"2026-10-03 11:17:37"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/9fc87899276af941ecf3045798887db7deb85605","name":"https://git.kernel.org/stable/c/9fc87899276af941ecf3045798887db7deb85605","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/75f5c412fa867efa0bf9b646bffe0d912109e84a","name":"https://git.kernel.org/stable/c/75f5c412fa867efa0bf9b646bffe0d912109e84a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214","name":"https://git.kernel.org/stable/c/f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f7748b551010c021d92f0125e37f32ac0c376d8a","name":"https://git.kernel.org/stable/c/f7748b551010c021d92f0125e37f32ac0c376d8a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-72315","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72315","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0e4b8faaaebe3137bec5723ef2b3cb0437fb38fd f7748b551010c021d92f0125e37f32ac0c376d8a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f655467a9973f964b267871e5fef533ad5014494 9fc87899276af941ecf3045798887db7deb85605 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 340cea84f691c5206561bb2e0147158fe02070be f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 340cea84f691c5206561bb2e0147158fe02070be 75f5c412fa867efa0bf9b646bffe0d912109e84a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 708c276f516d27beaded7f372ac8111cee43926c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0629a1a187e424373364d681b42b101894bdb548 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30afc6ea72cc6cf7c8d579e79b64232801c38d08 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.12.78 6.12.112 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.18.20 6.18.54 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.1.167 6.2 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.6.130 6.7 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.19.10 6.20 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.0","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.112 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.54 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.5 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"72315","cve":"CVE-2026-72315","epss":"0.001750000","percentile":"0.063440000","score_date":"2026-10-05","updated_at":"2026-10-06 00:14:18"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/smb/client/cifs_fs_sb.h","fs/smb/client/cifsfs.c","fs/smb/client/connect.c","fs/smb/client/file.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"f7748b551010c021d92f0125e37f32ac0c376d8a","status":"affected","version":"0e4b8faaaebe3137bec5723ef2b3cb0437fb38fd","versionType":"git"},{"lessThan":"9fc87899276af941ecf3045798887db7deb85605","status":"affected","version":"f655467a9973f964b267871e5fef533ad5014494","versionType":"git"},{"lessThan":"f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214","status":"affected","version":"340cea84f691c5206561bb2e0147158fe02070be","versionType":"git"},{"lessThan":"75f5c412fa867efa0bf9b646bffe0d912109e84a","status":"affected","version":"340cea84f691c5206561bb2e0147158fe02070be","versionType":"git"},{"status":"affected","version":"708c276f516d27beaded7f372ac8111cee43926c","versionType":"git"},{"status":"affected","version":"0629a1a187e424373364d681b42b101894bdb548","versionType":"git"},{"status":"affected","version":"30afc6ea72cc6cf7c8d579e79b64232801c38d08","versionType":"git"},{"lessThan":"6.12.112","status":"affected","version":"6.12.78","versionType":"semver"},{"lessThan":"6.18.54","status":"affected","version":"6.18.20","versionType":"semver"},{"lessThan":"6.2","status":"affected","version":"6.1.167","versionType":"semver"},{"lessThan":"6.7","status":"affected","version":"6.6.130","versionType":"semver"},{"lessThan":"6.20","status":"affected","version":"6.19.10","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/smb/client/cifs_fs_sb.h","fs/smb/client/cifsfs.c","fs/smb/client/connect.c","fs/smb/client/file.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"7.0"},{"lessThan":"7.0","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.112","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.54","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.5","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.112","versionStartIncluding":"6.12.78","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.54","versionStartIncluding":"6.18.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.5","versionStartIncluding":"7.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"7.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.167","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.130","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19.10","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix busy dentry warning on unmount after DIO\n\nCommit c68337442f03 (\"cifs: Fix busy dentry used after unmounting\") fixed\nthe issue in cifs where deferred close of a file led to a dentry reference\ncount not being released in umount, by flushing deferredclose_wq in\ncifs_kill_sb() to solve it.\n\nHowever, the cifs DIO path suffers from the same busy-dentry problem caused\nby a delayed dentry reference-count release:\n\n\t[dio]\t\t\t[cifsd]\t\t\t[close + umount]\nnetfs_unbuffered_write_iter_locked\n...\n\t\t\t\tcifs_demultiplex_thread\n netfs_unbuffered_write\n  cifs_issue_write\n  netfs_wait_for_in_progress_stream [1]\n\t\t\t\t...\n\t\t\t\t netfs_write_subrequest_terminated\n\t\t\t\t  netfs_subreq_clear_in_progress\n\t\t\t\t   netfs_wake_collector // wake [1]\n\t\t\t\t  netfs_put_subrequest\n netfs_put_request\n  queue_work(system_dfl_wq, xxx) [2]\n // dio write return\t\t\t\t\tcifs_close\n\t\t\t\t\t\t\t _cifsFileInfo_put\n\t\t\t\t\t\t\t  // cfile->count 2->1\n\t\t\t\t\t\t\t  --cfile->count [3]\n\n\t\t\t\t\t\t\t// umount\n\t\t\t\t\t\t\tcifs_kill_sb\n\t\t\t\t\t\t\t kill_anon_super\n\t\t\t\t\t\t\t  // warning triggered!\n\t\t\t\t\t\t\t  shrink_dcache_for_umount [4]\n[system_dfl_wq] [5]\nnetfs_free_request\n ...\n _cifsFileInfo_put\n  // cfile->count 1->0\n  --cfile->count\n  queue_work(fileinfo_put_wq, xxx)\n\n[fileinfo_put_wq] [6]\ncifsFileInfo_put_work\n cifsFileInfo_put_final\n  dput\n\nIf the umount path is triggered before [5], it results warning:\nBUG: Dentry 00000000eab1f070{i=9a917b66ae404fec,n=test}  still in use (1)\n[unmount of cifs cifs]\n\nThe existing per-inode ictx->io_count wait in cifs_evict_inode() does not\nhelp: it lives in the inode eviction path, which runs after\nshrink_dcache_for_umount() has already warned about the busy dentries.\n\nFix it by adding a per-superblock outstanding-rreq counter that is\nincremented in cifs_init_request() and decremented in cifs_free_request().\nIn cifs_kill_sb(), before kill_anon_super(), wait for this counter to reach\n0 - which guarantees that all cleanup_work for this sb have run and thus\nall relevant cfile puts are queued on fileinfo_put_wq or serverclose_wq.\nThen drain the workqueue so the dentry refs are dropped.\n\nThis is a targeted wait, not a flush of the system-wide system_dfl_wq."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The flaw is reached through local VFS syscalls (open with O_DIRECT, pwrite, close, umount) on the in-kernel CIFS/SMB3 client mount teardown path, not via remote SMB packet handling or ksmbd server code.\nAC:L - The attacker controls both sides of the race by issuing concurrent O_DIRECT writes and close/umount from separate threads, can flood system_dfl_wq to widen the cleanup delay window, and can retry until the post-pwrite/pre-cleanup_work window is hit.\nPR:L - Exploitation requires only a local user with write access to files on an already-mounted CIFS/SMB3 share; mount/umount can be performed by the same attacker with namespace capabilities or triggered by autofs lazy-unmount on shared enterprise home-directory mounts.\nUI:N - No victim interaction is required; the attacker directly drives the open/pwrite/close/umount syscall sequence in a tight loop without relying on another user to open files or perform any action.\nS:U - Impact is confined to kernel heap corruption and privilege escalation within the same host; this is not a VM escape, sandbox escape, or cross-security-authority boundary flaw.\nC:H - Delayed netfs cleanup causes cifsFileInfo_put_final() to dereference dentry, inode, and cifsInodeInfo structures after superblock teardown has begun, constituting a use-after-free that can be leveraged for arbitrary kernel memory read.\nI:H - Post-unmount cifsFileInfo_put_final() performs lock operations and list manipulation on freed kernel objects via fileinfo_put_wq, enabling heap metadata corruption and control-flow hijacking for arbitrary write or code execution.\nA:H - The race triggers WARN in shrink_dcache_for_umount during umount, and subsequent use-after-free in the deferred dentry put worker can cause kernel oops, panic, or hang."}]}],"providerMetadata":{"dateUpdated":"2026-10-03T10:55:48.520Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/f7748b551010c021d92f0125e37f32ac0c376d8a"},{"url":"https://git.kernel.org/stable/c/9fc87899276af941ecf3045798887db7deb85605"},{"url":"https://git.kernel.org/stable/c/f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214"},{"url":"https://git.kernel.org/stable/c/75f5c412fa867efa0bf9b646bffe0d912109e84a"}],"title":"smb: client: fix busy dentry warning on unmount after DIO","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-72315","datePublished":"2026-08-15T05:55:29.761Z","dateReserved":"2026-08-09T03:40:39.919Z","dateUpdated":"2026-10-03T10:55:48.520Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:22:04","lastModifiedDate":"2026-10-03 11:17:37","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"72315","Ordinal":"1","Title":"smb: client: fix busy dentry warning on unmount after DIO","CVE":"CVE-2026-72315","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"72315","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix busy dentry warning on unmount after DIO\n\nCommit c68337442f03 (\"cifs: Fix busy dentry used after unmounting\") fixed\nthe issue in cifs where deferred close of a file led to a dentry reference\ncount not being released in umount, by flushing deferredclose_wq in\ncifs_kill_sb() to solve it.\n\nHowever, the cifs DIO path suffers from the same busy-dentry problem caused\nby a delayed dentry reference-count release:\n\n\t[dio]\t\t\t[cifsd]\t\t\t[close + umount]\nnetfs_unbuffered_write_iter_locked\n...\n\t\t\t\tcifs_demultiplex_thread\n netfs_unbuffered_write\n  cifs_issue_write\n  netfs_wait_for_in_progress_stream [1]\n\t\t\t\t...\n\t\t\t\t netfs_write_subrequest_terminated\n\t\t\t\t  netfs_subreq_clear_in_progress\n\t\t\t\t   netfs_wake_collector // wake [1]\n\t\t\t\t  netfs_put_subrequest\n netfs_put_request\n  queue_work(system_dfl_wq, xxx) [2]\n // dio write return\t\t\t\t\tcifs_close\n\t\t\t\t\t\t\t _cifsFileInfo_put\n\t\t\t\t\t\t\t  // cfile->count 2->1\n\t\t\t\t\t\t\t  --cfile->count [3]\n\n\t\t\t\t\t\t\t// umount\n\t\t\t\t\t\t\tcifs_kill_sb\n\t\t\t\t\t\t\t kill_anon_super\n\t\t\t\t\t\t\t  // warning triggered!\n\t\t\t\t\t\t\t  shrink_dcache_for_umount [4]\n[system_dfl_wq] [5]\nnetfs_free_request\n ...\n _cifsFileInfo_put\n  // cfile->count 1->0\n  --cfile->count\n  queue_work(fileinfo_put_wq, xxx)\n\n[fileinfo_put_wq] [6]\ncifsFileInfo_put_work\n cifsFileInfo_put_final\n  dput\n\nIf the umount path is triggered before [5], it results warning:\nBUG: Dentry 00000000eab1f070{i=9a917b66ae404fec,n=test}  still in use (1)\n[unmount of cifs cifs]\n\nThe existing per-inode ictx->io_count wait in cifs_evict_inode() does not\nhelp: it lives in the inode eviction path, which runs after\nshrink_dcache_for_umount() has already warned about the busy dentries.\n\nFix it by adding a per-superblock outstanding-rreq counter that is\nincremented in cifs_init_request() and decremented in cifs_free_request().\nIn cifs_kill_sb(), before kill_anon_super(), wait for this counter to reach\n0 - which guarantees that all cleanup_work for this sb have run and thus\nall relevant cfile puts are queued on fileinfo_put_wq or serverclose_wq.\nThen drain the workqueue so the dentry refs are dropped.\n\nThis is a targeted wait, not a flush of the system-wide system_dfl_wq.","Type":"Description","Title":"smb: client: fix busy dentry warning on unmount after DIO"}]}}}