CVE-2026-98405 (GCVE-0-2026-98405)
Vulnerability from cvelistv5
Published
2026-10-14 13:27
Modified
2026-10-24 14:08
Severity ?
8.1 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix missing iov bounds check in parse_posix_sids() In parse_posix_sids(), sidsbuf_end is calculated using the server-supplied out_len without being validated against the actual length of the received iov (iov_len). If a server provides an inflated out_len, sidsbuf_end will point past the end of the iov. This defeats the bounds guards in posix_info_sid_size(), allowing out-of-bounds reads into adjacent kernel memory. Fix this by rejecting responses where the calculated sidsbuf_end would exceed the received iov boundaries or cause pointer wraparound.
References
Impacted products
Vendor Product Version
Linux Linux Version: a90f37e3d7acfd9824f162830583bbf7846fe252
Version: 858e74876c5cbff1dfd5bace99e32fbce2abd4b5
Version: 858e74876c5cbff1dfd5bace99e32fbce2abd4b5
Version: 858e74876c5cbff1dfd5bace99e32fbce2abd4b5
Version: 858e74876c5cbff1dfd5bace99e32fbce2abd4b5
Version: 6.6.32   ≤
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{
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      "cpeApplicability": [
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          "nodes": [
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix missing iov bounds check in parse_posix_sids()\n\nIn parse_posix_sids(), sidsbuf_end is calculated using the server-supplied\nout_len without being validated against the actual length of the received\niov (iov_len).\n\nIf a server provides an inflated out_len, sidsbuf_end will point past the\nend of the iov. This defeats the bounds guards in posix_info_sid_size(),\nallowing out-of-bounds reads into adjacent kernel memory.\n\nFix this by rejecting responses where the calculated sidsbuf_end would\nexceed the received iov boundaries or cause pointer wraparound."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - A malicious SMB server supplies the malformed OutputBufferLength and SID payload in an SMB2 QUERY_INFO response over TCP; cifs_root_iget() or cifs_getattr() reaches smb2_query_path_info(), smb2_compound_op(), then parse_posix_sids().\nAC:L - The server can place a valid SID header at the iov boundary and set num_subauth so parse_posix_sids() copies up to 68 bytes beyond it. Once the POSIX mount exists, triggering is deterministic and requires no race or uncontrollable heap state.\nPR:N - Session setup and tree connect precede compound_send_recv(), but the attacker is the SMB server endpoint and needs no account or capability on the client to choose the QUERY_INFO response.\nUI:R - The victim must mount the attacker-controlled share with the posix option, which sets ctx-\u003elinux_ext; cifs_read_super() then calls cifs_root_iget(), which immediately issues the vulnerable POSIX metadata query.\nS:U - The out-of-bounds access occurs in the SMB client and affects the same host kernel executing parse_posix_sids(); it crosses no VM, IOMMU, or sandbox security boundary.\nC:H - An inflated end pointer defeats posix_info_sid_size() bounds checks, allowing each owner or group SID memcpy() to consume up to 68 bytes of adjacent kernel memory and pass those bytes into SID/idmap processing.\nI:N - posix_info_sid_size() caps num_subauth at 15, so each memcpy() remains within its destination struct smb_sid; the defect performs out-of-bounds reads but provides no out-of-bounds write or control-flow modification.\nA:H - By ending the received iov at a SID header while claiming a larger OutputBufferLength, the server makes posix_info_sid_size() and memcpy() access beyond the receive allocation, which can fault and oops or panic the client kernel."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:08:44.159Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/d91b9a3b2b38e5ac1b51e9e5b23fe53ad7b49644"
        },
        {
          "url": "https://git.kernel.org/stable/c/b862996e5105be1293da9cdc85da77b76021c3bd"
        },
        {
          "url": "https://git.kernel.org/stable/c/2f8ed71aaaba3bc8b19cd9930cc62e63e142b299"
        },
        {
          "url": "https://git.kernel.org/stable/c/eac6917a42899aad0617bbf04798c5dd946a1fe5"
        },
        {
          "url": "https://git.kernel.org/stable/c/b09d092eb24ad0110f16a9b7c1ed5d2a0c1733dc"
        }
      ],
      "title": "smb: client: fix missing iov bounds check in parse_posix_sids()",
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98405",
    "datePublished": "2026-10-14T13:27:40.589Z",
    "dateReserved": "2026-09-25T10:25:14.347Z",
    "dateUpdated": "2026-10-24T14:08:44.159Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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