GHSA-WFFX-7972-VW67
Vulnerability from github – Published: 2026-09-17 18:31 – Updated: 2026-10-30 15:33In the Linux kernel, the following vulnerability has been resolved:
ksmbd: bound smb_check_perm_dacl() ACE walks by DACL size
smb_check_perm_dacl() validates that the DACL fits inside the NT security descriptor, but then bounds its two ACE walks by the remaining NTSD length (acl_size) rather than the DACL's declared size (pdacl_size).
When pdacl->size is smaller than the trailing NTSD buffer, bytes after the declared DACL boundary - still inside the stored security descriptor - are parsed as ACEs during access checks. A crafted DACL can place an access-granting ACE beyond pdacl->size, and the current code accepts it during SMB2_CREATE access validation, while parse_dacl() and smb_inherit_dacl() stop at pdacl_size.
Bound both ACE walks by pdacl_size to match the DACL boundary semantics used elsewhere in the server.
Validation: - semantic KUnit harness shows the post-boundary ACE is selected before the fix and rejected (EACCES) after it - linux master (7.2-rc6), x86_64
{
"affected": [],
"aliases": [
"CVE-2026-90153"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:17:08Z",
"severity": "HIGH"
},
"details": "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\u0027s declared\nsize (pdacl_size).\n\nWhen pdacl-\u003esize 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-\u003esize, 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",
"id": "GHSA-wffx-7972-vw67",
"modified": "2026-10-30T15:33:33Z",
"published": "2026-09-17T18:31:52Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90153"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/79decd88dd3f0d42e7fb0689b1a7853bfa302459"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8e4f75e979c1d9a51b0a48ac33d0cfd5f039ec67"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/930dcdd888eabf166589e020dcbf6d15b5e13305"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a2051ffe452afad52f580b85a3fd8851933b1e7c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a29f57a14c939586d84d7fd6a029bd1fd170098f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a4a307d149327dad5fb25187e1b03cebd1b04de6"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
]
}
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