Fortinet Fortigate LDAP authentication bypass in Agentless VPN and FSSO (FG-IR-25-1052)

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

include('compat.inc');

if (description)
{
  script_id(298512);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/02/13");

  script_cve_id("CVE-2026-22153");
  script_xref(name:"IAVA", value:"2026-A-0156");

  script_name(english:"Fortinet Fortigate LDAP authentication bypass in Agentless VPN and FSSO (FG-IR-25-1052)");

  script_set_attribute(attribute:"synopsis", value:
"Fortinet Firewall is missing one or more security-related updates.");
  script_set_attribute(attribute:"description", value:
"The version of Fortigate installed on the remote host is prior to tested version. It is, therefore, affected by a
vulnerability as referenced in the FG-IR-25-1052 advisory.

  - An Authentication Bypass by Primary Weakness vulnerability [CWE-305] vulnerability in Fortinet FortiOS
    7.6.0 through 7.6.4 may allow an unauthenticated attacker to bypass LDAP authentication of Agentless VPN
    or FSSO policy, when the remote LDAP server is configured in a specific way. (CVE-2026-22153)

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://www.fortiguard.com/psirt/FG-IR-25-1052");
  script_set_attribute(attribute:"solution", value:
"For 7.6.x, upgrade to Fortigate version 7.6.5 or later.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/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:H/PR:N/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-2026-22153");

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

  script_set_attribute(attribute:"potential_vulnerability", value:"true");
  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:fortinet:fortios");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

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

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

  script_dependencies("fortinet_version.nbin");
  script_require_keys("Host/Fortigate/model", "Host/Fortigate/version", "Settings/ParanoidReport");

  exit(0);
}

include('vcf_extras_fortios.inc');

# Since there's a workaround specified in the advisory, we're making this require paranoid.
if (report_paranoia < 2) audit(AUDIT_PARANOID);

var app_name = 'Fortigate';
var app_info = vcf::get_app_info(app:app_name, kb_ver:'Host/Fortigate/version');
vcf::fortios::verify_product_and_model(product_name:app_name);

var constraints = [
  { 'min_version' : '7.6.0', 'max_version' : '7.6.4', 'fixed_version' : '7.6.5' }
];

vcf::check_version_and_report(
    app_info:app_info,
    constraints:constraints,
    severity:SECURITY_HOLE
);