CVE-2026-64394

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Unlike the FSCTL data arms this\nis a metadata/xattr operation, so there is no FMODE_WRITE VFS backstop \u2014\nthe missing fp->daccess check is the entire gate.\n\nSetting a security descriptor is the WRITE_DAC / WRITE_OWNER operation, so\nrequire at least one of those on the handle before re-permissioning the\nfile. -EACCES is mapped to STATUS_ACCESS_DENIED by smb2_set_info()."}], "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:H", "baseScore": 8.8, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:N - The vulnerable SMB2 SET_INFO handler is remotely reachable through ksmbd over TCP port 445.\nAC:L - An attacker can deterministically open an attribute-only handle and submit a crafted security descriptor, with no race or uncontrollable condition.\nPR:L - A valid SMB session, writable tree connection, and permission to open the target with FILE_WRITE_ATTRIBUTES are required, but no administrative privileges are needed.\nUI:N - The attacker directly sends the SMB requests without requiring any victim action.\nS:U - The bypass affects files governed by the same host and ksmbd share security authority and does not cross a virtualization or sandbox boundary.\nC:H - The attacker can rewrite the DACL and mode to grant read access, potentially disclosing complete protected files within the share.\nI:H - The attacker can grant itself write or delete rights and subsequently modify or destroy protected file contents, ownership metadata, and ACLs.\nA:H - The attacker can deny legitimate access or grant itself sufficient rights to corrupt or destroy affected share data, causing complete loss of availability for those resources."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/smb/server/smb2pdu.c"], "versions": [{"version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "0848b1d8b403f530878195dcbe241a2fddb9d0e1", "status": "affected", "versionType": "git"}, {"version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "e6aa731f1b4b3e08caebf66a99f04b22bdab2e99", "status": "affected", "versionType": "git"}, {"version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "9ab2ffd3ed3d4ca1667c52de27026ddabc11e537", "status": "affected", "versionType": "git"}, {"version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "f56535db508ead8dec1c481ad93d7d8acd8f8f1e", "status": "affected", "versionType": "git"}, {"version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "aae600cdaffc6d9ce97645f129799a103a97d06d", "status": "affected", "versionType": "git"}, {"version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "44df157a1183a7f746caa970c169255da5ac61f8", "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/smb2pdu.c"], "versions": [{"version": "5.15", "status": "affected"}, {"version": "0", "lessThan": "5.15", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.178", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.96", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.39", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.4", "lessThanOrEqual": "7.1.*", "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": "6.1.178"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.6.145"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.12.96"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.18.39"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "7.1.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/0848b1d8b403f530878195dcbe241a2fddb9d0e1"}, {"url": "https://git.kernel.org/stable/c/e6aa731f1b4b3e08caebf66a99f04b22bdab2e99"}, {"url": "https://git.kernel.org/stable/c/9ab2ffd3ed3d4ca1667c52de27026ddabc11e537"}, {"url": "https://git.kernel.org/stable/c/f56535db508ead8dec1c481ad93d7d8acd8f8f1e"}, {"url": "https://git.kernel.org/stable/c/aae600cdaffc6d9ce97645f129799a103a97d06d"}, {"url": "https://git.kernel.org/stable/c/44df157a1183a7f746caa970c169255da5ac61f8"}], "title": "ksmbd: add a WRITE_DAC/WRITE_OWNER check to SMB2 SET_INFO SECURITY", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

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Unlike the FSCTL data arms this\nis a metadata/xattr operation, so there is no FMODE_WRITE VFS backstop \u2014\nthe missing fp->daccess check is the entire gate.\n\nSetting a security descriptor is the WRITE_DAC / WRITE_OWNER operation, so\nrequire at least one of those on the handle before re-permissioning the\nfile. -EACCES is mapped to STATUS_ACCESS_DENIED by smb2_set_info()."}], "id": "CVE-2026-64394", "lastModified": "2026-09-04T15:31:40.967", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.8, "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:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-07-25T10:17:22.790", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/0848b1d8b403f530878195dcbe241a2fddb9d0e1"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/44df157a1183a7f746caa970c169255da5ac61f8"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/9ab2ffd3ed3d4ca1667c52de27026ddabc11e537"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/aae600cdaffc6d9ce97645f129799a103a97d06d"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/e6aa731f1b4b3e08caebf66a99f04b22bdab2e99"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/f56535db508ead8dec1c481ad93d7d8acd8f8f1e"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "NVD-CWE-noinfo"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: ksmbd: add a WRITE_DAC/WRITE_OWNER check to SMB2 SET_INFO SECURITY", "id": "2507217", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2507217"}, "csaw": false, "cwe": "CWE-266", "details": ["A flaw was found in the Linux kernel's ksmbd component. This vulnerability allows a remote attacker to bypass intended access controls. By opening a file handle with limited write attributes, an attacker can use the SMB2 SET_INFO SECURITY operation to rewrite the file's access control list (DACL) and owner. This enables the attacker to grant themselves unauthorized permissions, leading to privilege escalation and potential unauthorized access to sensitive file operations."], "name": "CVE-2026-64394", "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"}], "public_date": "2026-07-25T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-64394\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-64394\nhttps://lore.kernel.org/linux-cve-announce/2026072528-CVE-2026-64394-9294@gregkh/T"]}

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