GHSA-VFWC-R92W-JP29
Vulnerability from github – Published: 2026-09-25 12:31 – Updated: 2026-09-25 12:31In the Linux kernel, the following vulnerability has been resolved:
smb: client: avoid using uninitialized SIDs in cifs_posix_to_fattr()
cifs_posix_to_fattr() ignores the return value of posix_info_parse(). When a malformed POSIX directory entry is encountered (e.g. invalid SID lengths from an untrusted server), posix_info_parse() returns -1 without populating the 'parsed' struct. The uninitialized stack memory in parsed.owner and parsed.group is then passed to sid_to_id(), which processes the garbage bytes and passes them to request_key() to construct a SID string, potentially leaking kernel stack contents to the userspace idmap daemon.
Fix this by checking the return value and skipping the SID-to-id mapping when parsing fails. The remaining fattr fields (timestamps, mode, etc.) are populated directly from the 'info' pointer so they are unaffected.
{
"affected": [],
"aliases": [
"CVE-2026-97554"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-25T11:17:05Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: avoid using uninitialized SIDs in cifs_posix_to_fattr()\n\ncifs_posix_to_fattr() ignores the return value of posix_info_parse().\nWhen a malformed POSIX directory entry is encountered (e.g. invalid\nSID lengths from an untrusted server), posix_info_parse() returns -1\nwithout populating the \u0027parsed\u0027 struct. The uninitialized stack\nmemory in parsed.owner and parsed.group is then passed to\nsid_to_id(), which processes the garbage bytes and passes them to\nrequest_key() to construct a SID string, potentially leaking kernel\nstack contents to the userspace idmap daemon.\n\nFix this by checking the return value and skipping the SID-to-id\nmapping when parsing fails. The remaining fattr fields (timestamps,\nmode, etc.) are populated directly from the \u0027info\u0027 pointer so they\nare unaffected.",
"id": "GHSA-vfwc-r92w-jp29",
"modified": "2026-09-25T12:31:24Z",
"published": "2026-09-25T12:31:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-97554"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c9a8b60ce140a68d172452f418137fc7ddbae7db"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/da6e25842431982d5a53cf00d925b98c690f4467"
}
],
"schema_version": "1.4.0",
"severity": []
}
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