GHSA-F75P-6Q8J-P2F2
Vulnerability from github – Published: 2026-04-22 09:31 – Updated: 2026-06-19 15:33In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix OOB write in QUERY_INFO for compound requests
When a compound request such as READ + QUERY_INFO(Security) is received, and the first command (READ) consumes most of the response buffer, ksmbd could write beyond the allocated buffer while building a security descriptor.
The root cause was that smb2_get_info_sec() checked buffer space using ppntsd_size from xattr, while build_sec_desc() often synthesized a significantly larger descriptor from POSIX ACLs.
This patch introduces smb_acl_sec_desc_scratch_len() to accurately compute the final descriptor size beforehand, performs proper buffer checking with smb2_calc_max_out_buf_len(), and uses exact-sized allocation + iov pinning.
{
"affected": [],
"aliases": [
"CVE-2026-31432"
],
"database_specific": {
"cwe_ids": [
"CWE-787"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-04-22T09:16:21Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix OOB write in QUERY_INFO for compound requests\n\nWhen a compound request such as READ + QUERY_INFO(Security) is received,\nand the first command (READ) consumes most of the response buffer,\nksmbd could write beyond the allocated buffer while building a security\ndescriptor.\n\nThe root cause was that smb2_get_info_sec() checked buffer space using\nppntsd_size from xattr, while build_sec_desc() often synthesized a\nsignificantly larger descriptor from POSIX ACLs.\n\nThis patch introduces smb_acl_sec_desc_scratch_len() to accurately\ncompute the final descriptor size beforehand, performs proper buffer\nchecking with smb2_calc_max_out_buf_len(), and uses exact-sized\nallocation + iov pinning.",
"id": "GHSA-f75p-6q8j-p2f2",
"modified": "2026-06-19T15:33:07Z",
"published": "2026-04-22T09:31:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31432"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/075ea208c648cc2bcd616295b711d3637c61de45"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/515c2daab46021221bdf406bef19bc90a44ec617"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/850452af77f55d185f9445e1f7a1db53c5e4aad4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d48c64fb80ad78b3dd29fb7d79b6ec7bd72bfc09"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fda9522ed6afaec45cabc198d8492270c394c7bc"
}
],
"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:H",
"type": "CVSS_V3"
}
]
}
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