CVE-2026-99115 (GCVE-0-2026-99115)

Vulnerability from cvelistv5 – Published: 2026-10-28 10:34 – Updated: 2026-10-28 10:34
VLAI
Title
ksmbd: fill in FileSysIdentifier in FS_POSIX_INFORMATION
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fill in FileSysIdentifier in FS_POSIX_INFORMATION smb2_get_info_filesystem() reports 56 bytes for FS_POSIX_INFORMATION, that is the whole of FILE_SYSTEM_POSIX_INFO, but never assigns FileSysIdentifier. Those eight bytes go to the client as they are found in the response buffer. The buffer is zeroed on allocation, so a standalone request leaks nothing. A compound request can leak: the offset of the next response is advanced by the length pinned for the previous one, so a reply that was written into the buffer and then dropped in favour of the short error response of smb2_set_err_rsp() stays there, and the next reply is laid over it with only the header cleared. Report the file system id statfs() returned, which is what the field is for. FileSysIdentifier is __le64 and f_fsid is a pair of ints, so assemble the value first, val[0] as the low half, and convert it on the way out.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7033 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < beba2ef6f66a71f20531ac70a1acb0b221e362e9 (git)
Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < ab057f271ef60ff8163818badc3de75c480eca07 (git)
Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < db2267b27c054a6c2151ff7fbb67927e784f31d6 (git)
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Linux Linux Affected: 5.15
Unaffected: 0 , < 5.15 (semver)
Unaffected: 6.18.59 , ≤ 6.18.* (semver)
Unaffected: 7.2.13 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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        {
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          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smb2pdu.c"
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              "operator": "OR"
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      "descriptions": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fill in FileSysIdentifier in FS_POSIX_INFORMATION\n\nsmb2_get_info_filesystem() reports 56 bytes for FS_POSIX_INFORMATION,\nthat is the whole of FILE_SYSTEM_POSIX_INFO, but never assigns\nFileSysIdentifier.  Those eight bytes go to the client as they are found\nin the response buffer.\n\nThe buffer is zeroed on allocation, so a standalone request leaks\nnothing.  A compound request can leak: the offset of the next response\nis advanced by the length pinned for the previous one, so a reply that\nwas written into the buffer and then dropped in favour of the short\nerror response of smb2_set_err_rsp() stays there, and the next reply is\nlaid over it with only the header cleared.\n\nReport the file system id statfs() returned, which is what the field is\nfor.  FileSysIdentifier is __le64 and f_fsid is a pair of ints, so\nassemble the value first, val[0] as the low half, and convert it on the\nway out."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T10:34:32.347Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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    "cveId": "CVE-2026-99115",
    "datePublished": "2026-10-28T10:34:32.347Z",
    "dateReserved": "2026-09-25T10:25:14.392Z",
    "dateUpdated": "2026-10-28T10:34:32.347Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "date": "2026-10-29",
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      "id": "msrc_CVE-2026-99115",
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      "product_status:known_affected": "1",
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      "title": "ksmbd: fill in FileSysIdentifier in FS_POSIX_INFORMATION",
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    },
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fill in FileSysIdentifier in FS_POSIX_INFORMATION\n\nsmb2_get_info_filesystem() reports 56 bytes for FS_POSIX_INFORMATION,\nthat is the whole of FILE_SYSTEM_POSIX_INFO, but never assigns\nFileSysIdentifier.  Those eight bytes go to the client as they are found\nin the response buffer.\n\nThe buffer is zeroed on allocation, so a standalone request leaks\nnothing.  A compound request can leak: the offset of the next response\nis advanced by the length pinned for the previous one, so a reply that\nwas written into the buffer and then dropped in favour of the short\nerror response of smb2_set_err_rsp() stays there, and the next reply is\nlaid over it with only the header cleared.\n\nReport the file system id statfs() returned, which is what the field is\nfor.  FileSysIdentifier is __le64 and f_fsid is a pair of ints, so\nassemble the value first, val[0] as the low half, and convert it on the\nway out."
          }
        ],
        "id": "CVE-2026-99115",
        "lastModified": "2026-10-28T11:17:31.023",
        "metrics": {},
        "published": "2026-10-28T11:17:31.023",
        "references": [
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      "title": "kernel: ksmbd: fill in FileSysIdentifier in FS_POSIX_INFORMATION",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-99115.json",
      "version": "3"
    }
  }
}



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