{"api_version":"1","generated_at":"2026-10-27T04:01:45+00:00","cve":"CVE-2026-93786","urls":{"html":"https://cve.report/CVE-2026-93786","api":"https://cve.report/api/cve/CVE-2026-93786.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-93786","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-93786"},"summary":{"title":"ksmbd: preserve VFS inherited POSIX ACL mask","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: preserve VFS inherited POSIX ACL mask\n\nThe VFS initializes a child's POSIX ACL from the parent's default ACL and\nthe requested creation mode. Do not mutate the parent ACL or overwrite the\nchild's VFS-computed access and default ACLs afterwards.\n\nThis preserves restrictive ACL_MASK entries and prevents SMB object creation\nfrom widening effective permissions.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-24 17:17:11","updated_at":"2026-10-03 11:17:48"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"8.1","severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","baseScore":8.1,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"NONE"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"8.1","severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","data":{"baseScore":8.1,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/e148e567a9252643baa125cb65d7ae9c2c6cf68a","name":"https://git.kernel.org/stable/c/e148e567a9252643baa125cb65d7ae9c2c6cf68a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4a19bb1c45667f5a5f6eff9cf6648e0f692d046f","name":"https://git.kernel.org/stable/c/4a19bb1c45667f5a5f6eff9cf6648e0f692d046f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/591acf171644de590cda245fd8595b473a1beb70","name":"https://git.kernel.org/stable/c/591acf171644de590cda245fd8595b473a1beb70","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0093909becbda22b62b39b654dbc607faed59cd0","name":"https://git.kernel.org/stable/c/0093909becbda22b62b39b654dbc607faed59cd0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-93786","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93786","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f44158485826c076335d6860d35872271a83791d 4a19bb1c45667f5a5f6eff9cf6648e0f692d046f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f44158485826c076335d6860d35872271a83791d 591acf171644de590cda245fd8595b473a1beb70 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f44158485826c076335d6860d35872271a83791d 0093909becbda22b62b39b654dbc607faed59cd0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f44158485826c076335d6860d35872271a83791d e148e567a9252643baa125cb65d7ae9c2c6cf68a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.15","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.158 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.111 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.53 6.18.* 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":"93786","cve":"CVE-2026-93786","epss":"0.003410000","percentile":"0.253460000","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/server/vfs.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"4a19bb1c45667f5a5f6eff9cf6648e0f692d046f","status":"affected","version":"f44158485826c076335d6860d35872271a83791d","versionType":"git"},{"lessThan":"591acf171644de590cda245fd8595b473a1beb70","status":"affected","version":"f44158485826c076335d6860d35872271a83791d","versionType":"git"},{"lessThan":"0093909becbda22b62b39b654dbc607faed59cd0","status":"affected","version":"f44158485826c076335d6860d35872271a83791d","versionType":"git"},{"lessThan":"e148e567a9252643baa125cb65d7ae9c2c6cf68a","status":"affected","version":"f44158485826c076335d6860d35872271a83791d","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/smb/server/vfs.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.15"},{"lessThan":"5.15","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.158","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.111","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.53","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":"6.6.158","versionStartIncluding":"5.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.111","versionStartIncluding":"5.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.53","versionStartIncluding":"5.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"5.15","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: preserve VFS inherited POSIX ACL mask\n\nThe VFS initializes a child's POSIX ACL from the parent's default ACL and\nthe requested creation mode. Do not mutate the parent ACL or overwrite the\nchild's VFS-computed access and default ACLs afterwards.\n\nThis preserves restrictive ACL_MASK entries and prevents SMB object creation\nfrom widening effective permissions."}],"metrics":[{"cvssV3_1":{"baseScore":8.1,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:N - SMB2 CREATE is dispatched to smb2_open() from ksmbd_conn_handler_loop() on TCP/445; after smb2_creat()/vfs_create() succeeds, smb2_open() calls ksmbd_vfs_inherit_posix_acl(), which overwrites the new object's POSIX ACL. That CREATE is the trigger; the damaged ACL then governs later SMB2 READ/WRITE.\nAC:L - ksmbd_vfs_inherit_posix_acl() does pace->e_perm=0x07 on the ACL_MASK entry of get_inode_acl(parent, ACL_TYPE_DEFAULT) then set_posix_acl()s that onto the child. A single SMB2 CREATE of a new name in a directory that already has a default POSIX ACL hits this with no race; CONFIG_FS_POSIX_ACL is the helper's own gate.\nPR:L - __handle_ksmbd_work() runs smb2_check_user_session() (SMB2_CREATE is not in the NEGOTIATE/SESSION_SETUP skip list) and smb2_get_ksmbd_tcon() before smb2_open(); that path also requires KSMBD_TREE_CONN_FLAG_WRITABLE and O_CREAT, so an authenticated share user with create rights is required, not a pre-auth client.\nUI:N - The attacking SMB client itself sends the SMB2 CREATE that makes smb2_open() call ksmbd_vfs_inherit_posix_acl() on the object it just created; no local user must mount a volume, open a file, or confirm any action.\nS:U - set_posix_acl() only replaces POSIX access/default ACL xattrs on the ksmbd-exported filesystem in this host kernel; the resulting permission widening stays in that same security authority and is not a VM escape, IOMMU bypass, or sandbox breakout.\nC:H - posix_acl_permission() grants named-user/group access as (entry.e_perm & mask.e_perm). Forcing ACL_MASK to 0x07 in ksmbd_vfs_inherit_posix_acl() drops that cap, so named principals whose default-ACL entries included ACL_READ can read new-object contents the original mask would have denied.\nI:H - The same set_posix_acl(ACL_TYPE_ACCESS) of the unmasked ACL makes ACL_WRITE in named entries effective on the new file; for directories it also writes ACL_TYPE_DEFAULT with mask 0x07, and get_inode_acl() returns the shared parent cache so the in-place e_perm store widens later inherits.\nA:N - The path stores a posix_acl_valid ACL whose ACL_MASK e_perm is 0x07 via set_posix_acl(); it does not NULL-deref, BUG, panic, hang, or leak kernel memory, so the ksmbd worker and host remain available."}]}],"providerMetadata":{"dateUpdated":"2026-10-03T10:57:21.384Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/4a19bb1c45667f5a5f6eff9cf6648e0f692d046f"},{"url":"https://git.kernel.org/stable/c/591acf171644de590cda245fd8595b473a1beb70"},{"url":"https://git.kernel.org/stable/c/0093909becbda22b62b39b654dbc607faed59cd0"},{"url":"https://git.kernel.org/stable/c/e148e567a9252643baa125cb65d7ae9c2c6cf68a"}],"title":"ksmbd: preserve VFS inherited POSIX ACL mask","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-93786","datePublished":"2026-09-24T16:02:19.798Z","dateReserved":"2026-09-18T17:59:28.788Z","dateUpdated":"2026-10-03T10:57:21.384Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-24 17:17:11","lastModifiedDate":"2026-10-03 11:17:48","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:L/UI:N/S:U/C:H/I:H/A:N","baseScore":8.1,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"NONE"},"exploitabilityScore":2.8,"impactScore":5.2}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"93786","Ordinal":"1","Title":"ksmbd: preserve VFS inherited POSIX ACL mask","CVE":"CVE-2026-93786","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"93786","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: preserve VFS inherited POSIX ACL mask\n\nThe VFS initializes a child's POSIX ACL from the parent's default ACL and\nthe requested creation mode. Do not mutate the parent ACL or overwrite the\nchild's VFS-computed access and default ACLs afterwards.\n\nThis preserves restrictive ACL_MASK entries and prevents SMB object creation\nfrom widening effective permissions.","Type":"Description","Title":"ksmbd: preserve VFS inherited POSIX ACL mask"}]}}}