Fortinet FortiClient Improper Link Resolution Before File Access (FG-IR-25-661)

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

include('compat.inc');

if (description)
{
  script_id(298942);
  script_version("1.5");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/09");

  script_cve_id("CVE-2025-62676");
  script_xref(name:"IAVA", value:"2026-A-0158");

  script_name(english:"Fortinet FortiClient Improper Link Resolution Before File Access (FG-IR-25-661)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Windows host is affected by a improper link resolution before file access vulnerability.");
  script_set_attribute(attribute:"description", value:
"The version of FortiClient installed on the remote host is prior to tested version. It is, therefore, affected by a
improper link resolution before file access vulnerability as referenced in the FG-IR-25-661 advisory.

  - An Improper Link Resolution Before File Access ('Link Following') vulnerability [CWE-59] vulnerability in 
    Fortinet FortiClientWindows 7.4.0 through 7.4.4, FortiClientWindows 7.2.0 through 7.2.12, 
    FortiClientWindows 7.0 all versions may allow a local low-privilege attacker to perform an arbitrary file 
    write with elevated permissions via crafted named pipe messages. (CVE-2025-62676)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://fortiguard.fortinet.com/psirt/FG-IR-25-661");
  script_set_attribute(attribute:"solution", value:
"Upgrade to FortiClient version 7.2.13, 7.4.5 or later.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/C:N/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:L/AC:L/PR:L/UI:N/S:U/C:N/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-2025-62676");

  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:"2025/02/10");
  script_set_attribute(attribute:"patch_publication_date", value:"2025/02/10");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/02/13");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:fortinet:forticlient");
  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("forticlient_detect.nbin");
  script_require_keys("installed_sw/FortiClient");

  exit(0);
}

include('vdf.inc');

# The free FortiClient VPN-only agent received the CVE-2025-62676 fix in a re-released 7.4.3 build
# (7.4.3.4726, later 7.4.3.4799), which use a distinct build band (4xxx) from the full client's
# 7.4.3 (7.4.3.1790.x). Carve out >= 7.4.3.4726 as fixed so the patched VPN-only agent is not
# flagged, while the full client (7.4.3.1790.x) and all 7.4.4.x remain vulnerable until 7.4.5.

# @tvdl-content
var vuln_data = {
  'metadata': {'spec_version': '1.0'},
  'checks': [
    {
      'product': {'name': 'FortiClient', 'type': 'app'},
      'check_algorithm': 'default',
      'constraints': [
        { 'min_version' : '7.0.0', 'max_version' : '7.0.999', 'fixed_display' : '7.2.13' },
        { 'min_version' : '7.2.0', 'fixed_version' : '7.2.13' },
        { 'min_version' : '7.4.0', 'fixed_version' : '7.4.3.4726', 'fixed_display' : '7.4.5 (or 7.4.3.4726 for the free VPN-only agent)' },
        { 'min_version' : '7.4.4', 'fixed_version' : '7.4.5' }
      ]
    }
  ]
};

var result = vdf::check_and_report(vuln_data:vuln_data, severity:SECURITY_WARNING);
vdf::handle_check_and_report_errors(vdf_result:result);