GHSA-XVVM-359F-6VGC
Vulnerability from github – Published: 2026-05-08 15:31 – Updated: 2026-06-19 15:33In the Linux kernel, the following vulnerability has been resolved:
smb: client: require a full NFS mode SID before reading mode bits
parse_dacl() treats an ACE SID matching sid_unix_NFS_mode as an NFS mode SID and reads sid.sub_auth[2] to recover the mode bits.
That assumes the ACE carries three subauthorities, but compare_sids() only compares min(a, b) subauthorities. A malicious server can return an ACE with num_subauth = 2 and sub_auth[] = {88, 3}, which still matches sid_unix_NFS_mode and then drives the sub_auth[2] read four bytes past the end of the ACE.
Require num_subauth >= 3 before treating the ACE as an NFS mode SID. This keeps the fix local to the special-SID mode path without changing compare_sids() semantics for the rest of cifsacl.
{
"affected": [],
"aliases": [
"CVE-2026-43350"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-08T14:16:45Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: require a full NFS mode SID before reading mode bits\n\nparse_dacl() treats an ACE SID matching sid_unix_NFS_mode as an NFS\nmode SID and reads sid.sub_auth[2] to recover the mode bits.\n\nThat assumes the ACE carries three subauthorities, but compare_sids()\nonly compares min(a, b) subauthorities. A malicious server can return\nan ACE with num_subauth = 2 and sub_auth[] = {88, 3}, which still\nmatches sid_unix_NFS_mode and then drives the sub_auth[2] read four\nbytes past the end of the ACE.\n\nRequire num_subauth \u003e= 3 before treating the ACE as an NFS mode SID.\nThis keeps the fix local to the special-SID mode path without changing\ncompare_sids() semantics for the rest of cifsacl.",
"id": "GHSA-xvvm-359f-6vgc",
"modified": "2026-06-19T15:33:10Z",
"published": "2026-05-08T15:31:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43350"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1592a6cd6f653f2d24572a6976c7a775b19f4940"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/23b54d6cc3ef30a51d984dc74364f24039ae2ecb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2757ad3e4b6f9e0fed4c7739594e702abc5cab21"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/38a69f08ee82c450d3e4168707fff2e317dc3ff7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8bd4cad3f458d11650d51c2d24b03fb1770ae6cc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b53b8e98c23310294fc45fc686db5ee860311896"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c8eef12af1cc73031639ea7cf16e0b10e2536b0b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f8488c07bea2431ee12a6067d736578064fa46b4"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H",
"type": "CVSS_V3"
}
]
}
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