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vuln-cve/data/2026/90xxx/CVE-2026-90153.json
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-90153",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2026-09-11T19:38:34.789Z",
"datePublished": "2026-09-17T16:06:46.296Z",
"dateUpdated": "2026-10-30T12:34:27.032Z"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux",
"dateUpdated": "2026-10-30T12:34:27.032Z"
},
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: bound smb_check_perm_dacl() ACE walks by DACL size\n\nsmb_check_perm_dacl() validates that the DACL fits inside the NT\nsecurity descriptor, but then bounds its two ACE walks by the\nremaining NTSD length (acl_size) rather than the DACL's declared\nsize (pdacl_size).\n\nWhen pdacl->size is smaller than the trailing NTSD buffer, bytes\nafter the declared DACL boundary - still inside the stored security\ndescriptor - are parsed as ACEs during access checks. A crafted\nDACL can place an access-granting ACE beyond pdacl->size, and the\ncurrent code accepts it during SMB2_CREATE access validation, while\nparse_dacl() and smb_inherit_dacl() stop at pdacl_size.\n\nBound both ACE walks by pdacl_size to match the DACL boundary\nsemantics used elsewhere in the server.\n\nValidation:\n- semantic KUnit harness shows the post-boundary ACE is selected\n before the fix and rejected (EACCES) after it\n- linux master (7.2-rc6), x86_64"
}
],
"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 - The crafted NTSD is carried in SMB2_SET_INFO (SMB2_O_INFO_SECURITY) or an SMB2_CREATE SMB2_CREATE_SD_BUFFER context; set_info_sec()/ksmbd_vfs_set_sd_xattr() store that buffer, and a later SMB2_CREATE in smb2_open() loads it into smb_check_perm_dacl() from ksmbd_conn_handler_loop() on TCP/445.\nAC:L - The attacker sets pdacl->size smaller than the NTSD tail, inflates num_aces, and places an ACCESS_ALLOWED ACE after the declared DACL; smb_check_perm_dacl() then walks those bytes on the next SMB2_CREATE with no race or attacker-uncontrollable layout.\nPR:L - __handle_ksmbd_work() requires check_user_session()/get_ksmbd_tcon() before smb2_open()/smb2_set_info(); planting the NTSD needs FILE_WRITE_DAC/FILE_WRITE_OWNER in smb2_set_info_sec() or create rights for SMB2_CREATE_SD_BUFFER on an acl-xattr share, not a pre-auth path.\nUI:N - The attacker alone sends the SMB2_SET_INFO or SMB2_CREATE SD_BUFFER that stores the NTSD and the SMB2_CREATE that calls smb_check_perm_dacl(); no victim mount, open, or other interactive step is required.\nS:U - smb_check_perm_dacl() only mis-evaluates the stored DACL for ksmbd file opens; the resulting access grant stays inside the kernel SMB server and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - The SID-matching ACE walk in smb_check_perm_dacl() can select a post-pdacl->size ACCESS_ALLOWED ACE for the caller or Everyone and apply its access_req, so SMB2_CREATE is authorized for FILE_READ_DATA that the declared DACL would have denied with -EACCES.\nI:H - The same extra ACE supplies attacker-controlled ace->access_req; ACCESS_ALLOWED with FILE_WRITE_DATA/GENERIC_ALL makes smb_check_perm_dacl() accept a write SMB2_CREATE that parse_dacl() and smb_inherit_dacl() never grant from the bounded DACL.\nA:N - Both walks stay inside the NTSD (acl_size from pntsd_size); the bug only returns success instead of -EACCES and does not oops, panic, hang, or corrupt memory."
}
]
}
],
"affected": [
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"fs/smb/server/smbacl.c"
],
"versions": [
{
"version": "8f0541186e9ad1b62accc9519cc2b7a7240272a7",
"lessThan": "930dcdd888eabf166589e020dcbf6d15b5e13305",
"status": "affected",
"versionType": "git"
},
{
"version": "8f0541186e9ad1b62accc9519cc2b7a7240272a7",
"lessThan": "a2051ffe452afad52f580b85a3fd8851933b1e7c",
"status": "affected",
"versionType": "git"
},
{
"version": "8f0541186e9ad1b62accc9519cc2b7a7240272a7",
"lessThan": "a29f57a14c939586d84d7fd6a029bd1fd170098f",
"status": "affected",
"versionType": "git"
},
{
"version": "8f0541186e9ad1b62accc9519cc2b7a7240272a7",
"lessThan": "a4a307d149327dad5fb25187e1b03cebd1b04de6",
"status": "affected",
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{
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{
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"lessThan": "79decd88dd3f0d42e7fb0689b1a7853bfa302459",
"status": "affected",
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},
{
"version": "cb69d4d6f709f87c94afa28ae64c501576692171",
"status": "affected",
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},
{
"version": "6e8f4abf584253cbaa596ea4ad13110cf61cd4c9",
"status": "affected",
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},
{
"version": "8e33102309bd6839b2e2e158f93a7b378cb4655d",
"status": "affected",
"versionType": "git"
},
{
"version": "5.15.62",
"lessThan": "5.16",
"status": "affected",
"versionType": "semver"
},
{
"version": "5.18.18",
"lessThan": "5.19",
"status": "affected",
"versionType": "semver"
},
{
"version": "5.19.2",
"lessThan": "5.20",
"status": "affected",
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}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"fs/smb/server/smbacl.c"
],
"versions": [
{
"version": "6.0",
"status": "affected"
},
{
"version": "0",
"lessThan": "6.0",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.1.191",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.6.157",
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.12.110",
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.18.52",
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "7.2.6",
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "7.3",
"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": "6.0",
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"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.0",
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "5.15.62"
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],
"references": [
{
"url": "https://git.kernel.org/stable/c/930dcdd888eabf166589e020dcbf6d15b5e13305"
},
{
"url": "https://git.kernel.org/stable/c/a2051ffe452afad52f580b85a3fd8851933b1e7c"
},
{
"url": "https://git.kernel.org/stable/c/a29f57a14c939586d84d7fd6a029bd1fd170098f"
},
{
"url": "https://git.kernel.org/stable/c/a4a307d149327dad5fb25187e1b03cebd1b04de6"
},
{
"url": "https://git.kernel.org/stable/c/8e4f75e979c1d9a51b0a48ac33d0cfd5f039ec67"
},
{
"url": "https://git.kernel.org/stable/c/79decd88dd3f0d42e7fb0689b1a7853bfa302459"
}
],
"title": "ksmbd: bound smb_check_perm_dacl() ACE walks by DACL size",
"x_generator": {
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}