{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64394","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-07-19T15:36:31.785Z","datePublished":"2026-07-25T08:50:39.797Z","dateUpdated":"2026-08-17T04:54:47.889Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-17T04:54:47.889Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: add a WRITE_DAC/WRITE_OWNER check to SMB2 SET_INFO SECURITY\n\ncommit cc57232cae23 (\"ksmbd: fix FSCTL permission bypass by adding a\npermission check for FSCTL_SET_SPARSE\") added a fp->daccess gate to\nfsctl_set_sparse and noted that \"similar handle-level checks exist in other\nfunctions but are missing here.\" The SMB2 SET_INFO SECURITY arm is one of\nthe missing ones, and the most security-relevant: smb2_set_info_sec() calls\nset_info_sec() with no per-handle access check.\n\nset_info_sec() (fs/smb/server/smbacl.c) re-permissions the file: it\nrewrites owner/group/mode via notify_change(), rewrites the POSIX ACL via\nset_posix_acl(), and on KSMBD_SHARE_FLAG_ACL_XATTR shares removes and\nrewrites the Windows security descriptor via ksmbd_vfs_set_sd_xattr().\nEvery other persistent-mutation arm of the sibling handler\nsmb2_set_info_file() checks fp->daccess first (FILE_WRITE_DATA /\nFILE_DELETE / FILE_WRITE_EA / FILE_WRITE_ATTRIBUTES); the SECURITY arm —\nwhich mutates the access control itself — is the only one with no gate.\n\nA client can therefore open a handle with FILE_WRITE_ATTRIBUTES only (no\nFILE_WRITE_DAC / FILE_WRITE_OWNER) and use SMB2_SET_INFO with InfoType\nSMB2_O_INFO_SECURITY to rewrite the file's DACL and owner, granting itself\naccess the handle's daccess never carried. Unlike the FSCTL data arms this\nis a metadata/xattr operation, so there is no FMODE_WRITE VFS backstop —\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"}}}}