PostgreSQL 17.x < 17.11 / 18.x < 18.6 GSSAPI Improper Message Integrity Enforcement

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# Portions Copyright (C) 1996-2019, The PostgreSQL Global Development Group
# Portions Copyright (C) 1994, The Regents of the University of California
# Permission to use, copy, modify, and distribute this software and its documentation for any purpose, without fee, and without a written agreement is hereby granted, provided that the above copyright notice and this paragraph and the following two paragraphs appear in all copies.
# IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
# THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
##

include('compat.inc');

if (description)
{
  script_id(342121);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/01");

  script_cve_id("CVE-2026-14681");
  script_xref(name:"IAVB", value:"2026-B-0238");

  script_name(english:"PostgreSQL 17.x < 17.11 / 18.x < 18.6 GSSAPI Improper Message Integrity Enforcement");

  script_set_attribute(attribute:"synopsis", value:
"The remote database server is affected by a security bypass vulnerability.");
  script_set_attribute(attribute:"description", value:
"The version of PostgreSQL installed on the remote host is 17 prior to 17.11 or 18 prior to 18.6. As such, it is
potentially affected by a security bypass vulnerability:

  - Improper enforcement of message integrity in PostgreSQL GSSAPI support allows a user to negotiate GSSAPI
    contrary to pg_hba.conf rules, via initial direct TLS connection. Despite a pg_hba.conf that appears to
    require GSSAPI, the connection may exchange data over TLS encryption alone. If the TLS settings are more
    permissive than the GSS settings, the connection may continue with lesser protection. Within major versions
    17-18, minor versions before PostgreSQL 18.6 and 17.11 are affected. Versions before PostgreSQL 17 are
    unaffected. (CVE-2026-14681)

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.postgresql.org/support/security/CVE-2026-14681");
  script_set_attribute(attribute:"solution", value:
"Upgrade to PostgreSQL 17.11 / 18.6 or later.");
  script_set_attribute(attribute:"agent", value:"all");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/Au:S/C:P/I:P/A:N");
  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:L/UI:N/S:U/C:L/I:L/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-14681");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2026-14681");

  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:"2026/08/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/13");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/01");

  script_set_attribute(attribute:"plugin_type", value:"combined");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:postgresql:postgresql");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_set_attribute(attribute:"thorough_tests", value:"true");
  script_end_attributes();

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

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

  script_dependencies("postgres_installed_windows.nbin", "postgres_installed_nix.nbin", "postgresql_version.nbin");
  script_require_ports("Services/postgresql", 5432, "installed_sw/PostgreSQL");

  exit(0);
}

include('vcf_extras_postgresql.inc');

var win_local = TRUE;
if (!get_kb_item('SMB/Registry/Enumerated'))
  win_local = FALSE;

var port = get_service(svc:'postgresql', default:5432);
var kb_base = 'database/' + port + '/postgresql/';
var kb_ver = NULL;
var kb_path = kb_base + 'version';
var ver = get_kb_item(kb_path);
if (!empty_or_null(ver)) kb_ver = kb_path;

var app_info = vcf::postgresql::get_app_info(app:'PostgreSQL', port:port, kb_ver:kb_ver, kb_base:kb_base, win_local:win_local);
vcf::check_granularity(app_info:app_info, sig_segments:2);

#  17.11 / 18.6 -- PostgreSQL 16 and earlier are unaffected
var constraints = [
  { 'min_version' : '17', 'fixed_version' : '17.11' },
  { 'min_version' : '18', 'max_version' : '18.4', 'fixed_version' : '18.6' }
];

vcf::postgresql::check_version_and_report(
  app_info:app_info,
  constraints:constraints,
  severity:SECURITY_WARNING
);