{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-93786", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-18T17:59:28.788Z", "datePublished": "2026-09-24T16:02:19.798Z", "dateUpdated": "2026-09-25T12:42:51.882Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-09-25T12:42:51.882Z"}, "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": {"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"}, "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."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/smb/server/vfs.c"], "versions": [{"version": "f44158485826c076335d6860d35872271a83791d", "lessThan": "591acf171644de590cda245fd8595b473a1beb70", "status": "affected", "versionType": "git"}, {"version": "f44158485826c076335d6860d35872271a83791d", "lessThan": "0093909becbda22b62b39b654dbc607faed59cd0", "status": "affected", "versionType": "git"}, {"version": "f44158485826c076335d6860d35872271a83791d", "lessThan": "e148e567a9252643baa125cb65d7ae9c2c6cf68a", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/smb/server/vfs.c"], "versions": [{"version": "5.15", "status": "affected"}, {"version": "0", "lessThan": "5.15", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.111", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.53", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.12.111"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.18.53"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "7.2"}]}]}], "references": [{"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"}}}}

{}

{"affected": [{"affectedData": [{"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": "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": "6.12.*", "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"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "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."}], "id": "CVE-2026-93786", "lastModified": "2026-09-25T13:17:19.157", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.2, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-09-24T17:17:11.243", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/0093909becbda22b62b39b654dbc607faed59cd0"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/591acf171644de590cda245fd8595b473a1beb70"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e148e567a9252643baa125cb65d7ae9c2c6cf68a"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: ksmbd: preserve VFS inherited POSIX ACL mask", "id": "2540469", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2540469"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-281", "details": ["A flaw was found in the Linux kernel's ksmbd (in-kernel Server Message Block) component. When creating new files or directories, ksmbd improperly modified inherited Access Control Lists (ACLs) by overwriting restrictive permission masks. An authenticated user creating objects on an SMB share could exploit this flaw to widen effective file permissions, potentially leading to unauthorized access to files and directories."], "name": "CVE-2026-93786", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Not affected", "package_name": "openshift/ose-rhel-coreos-8", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Not affected", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-09-24T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-93786\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-93786\nhttps://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93786.mbox"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,591acf171644de590cda245fd8595b473a1beb70)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,0093909becbda22b62b39b654dbc607faed59cd0)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,e148e567a9252643baa125cb65d7ae9c2c6cf68a)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,6.12.111)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,6.18.53)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.111,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.53,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2, *]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-09-24T19:45:17.642517+00:00", "updated": "2026-09-28T16:00:03.420963+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}