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        "name": "Kernel"
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  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53390.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix out-of-bounds read in smb_check_perm_dacl()\n\nThe permission-check ACE walk in smb_check_perm_dacl() validates the ACE\nheader size and caps sid.num_subauth at SID_MAX_SUB_AUTHORITIES, but it\nnever checks that ace-\u003esize is actually large enough to contain\nnum_subauth sub-authorities before compare_sids() dereferences them.\n\nCIFS_SID_BASE_SIZE covers the SID header up to but excluding the\nsub_auth[] array, and offsetof(struct smb_ace, sid) is the ACE header,\nso the existing guards only guarantee the 8-byte SID base, i.e. zero\nsub-authorities. compare_sids() then reads ace-\u003esid.sub_auth[i] for\ni \u003c min(local_sid-\u003enum_subauth, ace-\u003esid.num_subauth). The local\ncomparison SIDs (sid_everyone, sid_unix_NFS_mode, and the id_to_sid()\nresult) always have at least one sub-authority, and an attacker controls\nthe ACE revision and authority bytes (which lie within the in-bounds SID\nbase), so they can match one of those SIDs and force the sub_auth read.\n\nA crafted ACE with size == 16 and num_subauth \u003e= 1 placed at the tail of\nthe security descriptor therefore causes a heap out-of-bounds read of up\nto SID_MAX_SUB_AUTHORITIES * sizeof(__le32) bytes past the pntsd\nallocation. The security descriptor is loaded by ksmbd_vfs_get_sd_xattr()\ninto a buffer sized exactly to the on-disk data (kzalloc(sd_size) in\nndr_decode_v4_ntacl()), so the read lands past the allocation. The\nmalformed descriptor can be stored verbatim via SMB2_SET_INFO (the DACL\nis not normalised before being written to the security.NTACL xattr) and\nthe read fires on a subsequent SMB2_CREATE access check, making this\nreachable by an authenticated client on a share that uses ACL xattrs.\n\nAdd the missing num_subauth-versus-ace_size check, mirroring the\nidentical guards already present in the sibling parsers parse_dacl() and\nsmb_inherit_dacl().",
  "id": "CVE-2026-53390",
  "modified": "2026-07-22T05:30:08.083913072Z",
  "published": "2026-07-19T12:01:54.951Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1ef06004ed4bd6d3ed8c840d9d1a376b66d4935b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/36599894fa8536fefdf1e296c0af71b8b7226859"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7627ff8c4f9919f14de562b0160ab4ec9d80b1f7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/988c93d3bba066d8669143e6ec30bb2be9608d53"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d5c81a095c86fe507c032d08f3a8cfc518444927"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e36e35660adb9b8ef1435ac359151dda5f094c55"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53390.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53390"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "ksmbd: fix out-of-bounds read in smb_check_perm_dacl()"
}