Security Updates for Skype for Business (October 2026)

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

include('compat.inc');

if (description)
{
  script_id(366092);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/16");

  script_cve_id("CVE-2026-70297", "CVE-2026-83746", "CVE-2026-85873");
  script_xref(name:"MSKB", value:"5131692");
  script_xref(name:"MSKB", value:"5131693");
  script_xref(name:"MSKB", value:"5132779");
  script_xref(name:"MSFT", value:"MS26-5131692");
  script_xref(name:"MSFT", value:"MS26-5131693");
  script_xref(name:"MSFT", value:"MS26-5132779");

  script_name(english:"Security Updates for Skype for Business (October 2026)");

  script_set_attribute(attribute:"synopsis", value:
"The Microsoft Skype for Business installation on the remote host is affected by multiple vulnerabilities.");
  script_set_attribute(attribute:"description", value:
"The Microsoft Skype for Business installation on the remote host is missing security updates. It is,
therefore, affected by multiple vulnerabilities:

  - Absolute path traversal in Skype for Business and Microsoft Lync allows an authorized attacker to execute
    code over a network. (CVE-2026-70297)

  - Absolute path traversal in Skype for Business and Microsoft Lync allows an authorized attacker to elevate
    privileges over a network. (CVE-2026-83746)

  - Improper authorization in Skype for Business and Microsoft Lync allows an authorized attacker to elevate
    privileges over a network. (CVE-2026-85873)

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/5131692");
  script_set_attribute(attribute:"see_also", value:"https://support.microsoft.com/help/5131693");
  script_set_attribute(attribute:"see_also", value:"https://support.microsoft.com/help/5132779");
  script_set_attribute(attribute:"solution", value:
"Microsoft has released the following security updates to address this issue:
    - Update to version 6.0.9319.886
    - Update to version 7.0.2046.583
    - Update to version 7.0.2046.889");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/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:L/UI:N/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-2026-70297");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_cwe_id(36, 639);

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/10/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/10/13");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/15");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:microsoft:skype_for_business");
  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("office_installed.nasl", "microsoft_lync_server_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('smb_func.inc');
include('smb_hotfixes.inc');
include('smb_hotfixes_fcheck.inc');
include('install_func.inc');

get_kb_item_or_exit('SMB/MS_Bulletin_Checks/Possible');

var bulletin = 'MS26-10';
var kbs = make_list(
  '5131692',
  '5131693',
  '5132779'
);

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

get_kb_item_or_exit('installed_sw/Microsoft Lync');

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

var uninstall_list = get_kb_list('SMB/Registry/HKLM/SOFTWARE/Microsoft/Windows/CurrentVersion/Uninstall/*/DisplayName');

if (isnull(uninstall_list)) exit(1, 'Missing uninstall enumeration list.');

var vuln = FALSE;

var name_kb, prod, version_kb, kb, version, info;

foreach name_kb (keys(uninstall_list))
{
  prod = uninstall_list[name_kb];
  version_kb = name_kb - '/DisplayName' + '/DisplayVersion';
  if ('Skype for Business' >< prod)
  {
    if ('Server' >< prod && 'Core Components' >< prod)
    {
      if ('Subscription' >< prod)
      {
        version = get_kb_item(version_kb);
        if (!isnull(version) && (ver_compare(ver:version, minver:'7.0.2046.0', fix:'7.0.2046.889') < 0))
        {
          vuln = TRUE;
          kb = '5131692';
          info = '\n  Product           : ' + prod +
                 '\n  Installed Version : ' + version +
                 '\n  Fixed Version     : 7.0.2046.889\n';
          hotfix_add_report(info, bulletin:bulletin, kb:kb);
        }
      }
      else if ('2019' >< prod)
      {
        version = get_kb_item(version_kb);
        if (!isnull(version) && (ver_compare(ver:version, minver:'7.0.2046.0', fix:'7.0.2046.583') < 0))
        {
          vuln = TRUE;
          kb = '5131693';
          info = '\n  Product           : ' + prod +
                 '\n  Installed Version : ' + version +
                 '\n  Fixed Version     : 7.0.2046.583\n';
          hotfix_add_report(info, bulletin:bulletin, kb:kb);
        }
      }
      else if ('2015' >< prod)
      {
        version = get_kb_item(version_kb);
        if (!isnull(version) && (ver_compare(ver:version, minver:'6.0.9319.0', fix:'6.0.9319.886') < 0))
        {
          vuln = TRUE;
          kb = '5132779';
          info = '\n  Product           : ' + prod +
                 '\n  Installed Version : ' + version +
                 '\n  Fixed Version     : 6.0.9319.886\n';
          hotfix_add_report(info, bulletin:bulletin, kb:kb);
        }
      }
    }
  }
}

if (vuln)
{
  replace_kb_item(name:'SMB/Missing/'+bulletin, value:TRUE);
  hotfix_security_hole();
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}