KB5087539: Windows Server 2025 Security Update (May 2026)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.

#
# The descriptive text and package checks in this plugin were
# extracted from the Microsoft Security Updates API. The text
# itself is copyright (C) Microsoft Corporation.
##

include('compat.inc');

if (description)
{
  script_id(314355);
  script_version("1.5");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/06/23");

  script_cve_id(
    "CVE-2025-54518",
    "CVE-2026-21530",
    "CVE-2026-32161",
    "CVE-2026-32170",
    "CVE-2026-32209",
    "CVE-2026-33834",
    "CVE-2026-33835",
    "CVE-2026-33837",
    "CVE-2026-33838",
    "CVE-2026-33839",
    "CVE-2026-33840",
    "CVE-2026-33841",
    "CVE-2026-34329",
    "CVE-2026-34330",
    "CVE-2026-34331",
    "CVE-2026-34332",
    "CVE-2026-34333",
    "CVE-2026-34334",
    "CVE-2026-34336",
    "CVE-2026-34337",
    "CVE-2026-34338",
    "CVE-2026-34339",
    "CVE-2026-34340",
    "CVE-2026-34341",
    "CVE-2026-34342",
    "CVE-2026-34343",
    "CVE-2026-34344",
    "CVE-2026-34345",
    "CVE-2026-34347",
    "CVE-2026-34350",
    "CVE-2026-34351",
    "CVE-2026-35415",
    "CVE-2026-35416",
    "CVE-2026-35417",
    "CVE-2026-35418",
    "CVE-2026-35419",
    "CVE-2026-35420",
    "CVE-2026-35421",
    "CVE-2026-35422",
    "CVE-2026-35423",
    "CVE-2026-35424",
    "CVE-2026-40369",
    "CVE-2026-40377",
    "CVE-2026-40380",
    "CVE-2026-40382",
    "CVE-2026-40397",
    "CVE-2026-40398",
    "CVE-2026-40399",
    "CVE-2026-40401",
    "CVE-2026-40403",
    "CVE-2026-40405",
    "CVE-2026-40406",
    "CVE-2026-40407",
    "CVE-2026-40408",
    "CVE-2026-40410",
    "CVE-2026-40413",
    "CVE-2026-40414",
    "CVE-2026-40415",
    "CVE-2026-41088",
    "CVE-2026-41089",
    "CVE-2026-41095",
    "CVE-2026-41096",
    "CVE-2026-41097",
    "CVE-2026-42825",
    "CVE-2026-42896"
  );
  script_xref(name:"MSKB", value:"5087539");
  script_xref(name:"MSKB", value:"5087423");
  script_xref(name:"MSFT", value:"MS26-5087539");
  script_xref(name:"MSFT", value:"MS26-5087423");
  script_xref(name:"IAVA", value:"2026-A-0465");
  script_xref(name:"IAVA", value:"2026-A-0466");

  script_name(english:"KB5087539: Windows Server 2025 Security Update (May 2026)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Windows host is affected by multiple vulnerabilities.");
  script_set_attribute(attribute:"description", value:
"The remote Windows host is missing security update 5087539 or hotpatch 5087423. It is, therefore, affected by multiple vulnerabilities

  - Heap-based buffer overflow in Microsoft Windows DNS allows an unauthorized attacker to execute code over a
    network. (CVE-2026-41096)

  - Stack-based buffer overflow in Windows Netlogon allows an unauthorized attacker to execute code over a
    network. (CVE-2026-41089)

  - Heap-based buffer overflow in Windows Win32K - GRFX allows an authorized attacker to execute code locally.
    (CVE-2026-40403)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://support.microsoft.com/help/5087539");
  script_set_attribute(attribute:"solution", value:
"Apply Security Update 5087539 or hotpatch 5087423");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:P");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-41096");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2026-35418");
  script_set_attribute(attribute:"cvss4_score_source", value:"CVE-2025-54518");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/05/12");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/05/12");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/05/12");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:microsoft:windows_server_2025");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Windows : Microsoft Bulletins");

  script_copyright(english:"This script is Copyright (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("smb_check_rollup.nasl", "smb_hotfixes.nasl", "ms_bulletin_checks_possible.nasl");
  script_require_keys("SMB/MS_Bulletin_Checks/Possible");
  script_require_ports(139, 445, "Host/patch_management_checks");

  exit(0);
}

include('smb_func.inc');
include('smb_hotfixes.inc');
include('smb_hotfixes_fcheck.inc');
include('smb_reg_query.inc');

get_kb_item_or_exit('SMB/MS_Bulletin_Checks/Possible');

var bulletin = 'MS26-05';
var kbs = make_list(
  '5087539', '5087423'
);

if (get_kb_item('Host/patch_management_checks')) hotfix_check_3rd_party(bulletin:bulletin, kbs:kbs, severity:SECURITY_HOLE);

get_kb_item_or_exit('SMB/Registry/Enumerated');
get_kb_item_or_exit('SMB/WindowsVersion', exit_code:1);

if (hotfix_check_sp_range(win10:'0') <= 0) audit(AUDIT_OS_SP_NOT_VULN);

var share = hotfix_get_systemdrive(as_share:TRUE, exit_on_fail:TRUE);
if (!is_accessible_share(share:share)) audit(AUDIT_SHARE_FAIL, share);

# This plugin is for Windows Server 2025 only (version 4th component >= 32000)
# Windows 11 24H2/25H2 systems (< 32000) should use the KB5089549 plugin instead
var os_build = get_kb_item('SMB/WindowsVersionBuild');
var os_name = get_kb_item("SMB/ProductName");
if (os_build == '26100')
{
  var systemroot = hotfix_get_systemroot();
  var path = hotfix_append_path(path:systemroot + "\system32", value:"ntoskrnl.exe");
  var fver = hotfix_get_fversion(path:path);
  if (!isnull(fver) && fver['error'] == HCF_OK && !isnull(fver['version']))
  {
    var ver_parts = split(fver['version'], sep:'.', keep:FALSE);
    if ((max_index(ver_parts) >= 4 && int(ver_parts[3]) < 32000) && ('server' >!< tolower(os_name)))
    {
      # Windows 11 24H2/25H2 system - this plugin doesn't apply (use KB5089549)
      hotfix_check_fversion_end();
      audit(AUDIT_HOST_NOT, 'affected (Windows 11 - use KB5089549)');
    }
  }
}

var wmi_patch_found = get_kb_item("WMI/Installed/Hotfix/KB5087423");

if (
  smb_check_rollup(os:'10',
                   os_build:26100,
                   rollup_date:'05_2026',
                   bulletin:bulletin,
                   rollup_kb_list:[5087539, 5087423])
)
{
  if (!wmi_patch_found)
  {
    replace_kb_item(name:'SMB/Missing/'+bulletin, value:TRUE);
    hotfix_security_hole();
  }
  hotfix_check_fversion_end();
  exit(0);
}
else
{
  hotfix_check_fversion_end();
  audit(AUDIT_HOST_NOT, hotfix_get_audit_report());
}