PostgreSQL 16.x < 16.15 / 17.x < 17.11 / 18.x < 18.6 SCRAM Observable Response Discrepancy

#%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.
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# 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(342122);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/01");

  script_cve_id("CVE-2026-14672");
  script_xref(name:"IAVB", value:"2026-B-0238");

  script_name(english:"PostgreSQL 16.x < 16.15 / 17.x < 17.11 / 18.x < 18.6 SCRAM Observable Response Discrepancy");

  script_set_attribute(attribute:"synopsis", value:
"The remote database server is affected by an information disclosure vulnerability.");
  script_set_attribute(attribute:"description", value:
"The version of PostgreSQL installed on the remote host is 16 prior to 16.15, 17 prior to 17.11, or 18 prior to 18.6. As
such, it is potentially affected by an information disclosure vulnerability:

  - Observable response discrepancy in PostgreSQL SCRAM authentication allows an unauthenticated user to test
    the existence of a user via observing the SCRAM iteration count. This requires the probed user to have a
    non-default scram_iterations count, because the authentication challenge for a nonexistent user reports the
    default scram_iterations. Within major versions 16-18, minor versions before PostgreSQL 18.6, 17.11, and
    16.15 are affected. Versions before PostgreSQL 16 are unaffected. (CVE-2026-14672)

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-2026-14672");
  script_set_attribute(attribute:"solution", value:
"Upgrade to PostgreSQL 16.15 / 17.11 / 18.6 or later.");
  script_set_attribute(attribute:"agent", value:"all");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:N/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:L/PR:N/UI:N/S:U/C:L/I:N/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-2026-14672");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2026-14672");

  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);

#  16.15 / 17.11 / 18.6 -- PostgreSQL 15 and earlier are unaffected
var constraints = [
  { 'min_version' : '16', 'fixed_version' : '16.15' },
  { '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
);