Security Updates for Microsoft Excel Products C2R (September 2026)

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

include('compat.inc');

if (description)
{
  script_id(344559);
  script_version("1.3");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/11");

  script_cve_id(
    "CVE-2026-78518",
    "CVE-2026-81386",
    "CVE-2026-81387",
    "CVE-2026-81388",
    "CVE-2026-81389",
    "CVE-2026-81390",
    "CVE-2026-81391",
    "CVE-2026-81392",
    "CVE-2026-81393",
    "CVE-2026-81394",
    "CVE-2026-81395",
    "CVE-2026-81396",
    "CVE-2026-81397",
    "CVE-2026-81398",
    "CVE-2026-81399",
    "CVE-2026-81400",
    "CVE-2026-81401",
    "CVE-2026-81947",
    "CVE-2026-81948",
    "CVE-2026-81949",
    "CVE-2026-81950",
    "CVE-2026-81951",
    "CVE-2026-81953",
    "CVE-2026-81954",
    "CVE-2026-81956",
    "CVE-2026-81957",
    "CVE-2026-81958",
    "CVE-2026-81959",
    "CVE-2026-81960",
    "CVE-2026-85875"
  );
  script_xref(name:"IAVA", value:"2026-A-0959");

  script_name(english:"Security Updates for Microsoft Excel Products C2R (September 2026)");

  script_set_attribute(attribute:"synopsis", value:
"The Microsoft Excel Products are affected by multiple vulnerabilities.");
  script_set_attribute(attribute:"description", value:
"The Microsoft Excel Products are missing security updates. It is, therefore, affected by multiple
vulnerabilities:

  - Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to execute code over a
    network. (CVE-2026-78518)

  - Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code
    locally. (CVE-2026-81386, CVE-2026-81389, CVE-2026-81397, CVE-2026-81398, CVE-2026-81947, CVE-2026-81948,
    CVE-2026-81951, CVE-2026-81959, CVE-2026-81960)

  - Stack-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code
    locally. (CVE-2026-81388, CVE-2026-81396, CVE-2026-81953)

  - Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
    (CVE-2026-81954)

  - Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information
    locally. (CVE-2026-81390, CVE-2026-81392, CVE-2026-81393, CVE-2026-81395, CVE-2026-81400, CVE-2026-85875)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  # https://learn.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?5931548c");
  script_set_attribute(attribute:"solution", value:
"Microsoft has released patches to address these issues.

For Office 365, Office 2016 C2R, or Office 2019, ensure automatic
updates are enabled or open any office app and manually perform an
update.");
  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:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-78518");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/09/08");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/08");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/10");

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

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

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

  script_dependencies("office_installed.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('vcf_extras_office.inc');

var bulletin = 'MS26-09';

var constraints = [
  {'fixed_version':'16.0.20326.20144','channel':'Current'},
  {'fixed_version':'16.0.20326.20142','channel':'Enterprise Deferred','channel_version':'2608'},
  {'fixed_version':'16.0.20228.20226','channel':'Enterprise Deferred','channel_version':'2607'},
  {'fixed_version':'16.0.20131.20260','channel':'Enterprise Deferred'},
  {'fixed_version':'16.0.20326.20140','channel':'Deferred','channel_version':'2608'},
  {'fixed_version':'16.0.20228.20226','channel':'Deferred','channel_version':'2607'},
  {'fixed_version':'16.0.20131.20258','channel':'Deferred'},
  {'fixed_version':'16.0.20326.20144','channel':'2024 Retail'},
  {'fixed_version':'16.0.20326.20144','channel':'2021 Retail'},
  {'fixed_version':'16.0.17932.20976','channel':'LTSC 2024'},
  {'fixed_version':'16.0.14334.20906','channel':'LTSC 2021'},
  {'fixed_version':'16.0.10417.20207','channel':'2019 Volume'}
];

vcf::microsoft::office_product::check_version_and_report(
  constraints:constraints,
  severity:SECURITY_HOLE,
  bulletin:bulletin,
  subproduct:'Excel'
);