Elasticsearch 8.19.x < 8.19.20 / 9.0.x < 9.4.5 DoS (ESA-2026-81)

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

include('compat.inc');

if (description)
{
  script_id(338340);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/20");

  script_cve_id("CVE-2026-72679");
  script_cwe_id(674);

  script_name(english:"Elasticsearch 8.19.x < 8.19.20 / 9.0.x < 9.4.5 DoS (ESA-2026-81)");

  script_set_attribute(attribute:"synopsis", value:
"The remote host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The version of Elasticsearch installed on the remote host is 8.19.x prior to 8.19.20, or 9.0.x prior to 9.4.5. It is,
therefore, affected by a vulnerability as referenced in the ESA-2026-81 advisory.

  - Elasticsearch does not apply its configurable input length restriction to a user-supplied pattern accepted by
    an intervals query. Compiling a deeply nested pattern drives unbounded recursion that exhausts the thread stack
    and raises a fatal error, terminating the Elasticsearch node process and causing a denial of service for that
    node. An authenticated user holding only read-only privileges on a single searchable index can trigger the
    condition with one small search request. (CVE-2026-72679)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  # https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-security-update-esa-2026-81/389501
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?42fa34c4");
  script_set_attribute(attribute:"solution", value:
"Upgrade to Elasticsearch version 8.19.20 or 9.4.5 or later as appropriate for your release branch.");
  script_set_attribute(attribute:"agent", value:"unix");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/C:N/I:N/A:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-72679");

  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:"2026/08/20");

  script_set_attribute(attribute:"plugin_type", value:"combined");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:elasticsearch:elasticsearch");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:elastic:elasticsearch");
  script_set_attribute(attribute:"thorough_tests", value:"true");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

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

  script_dependencies("elasticsearch_detect.nbin", "elastic_elasticsearch_nix_installed.nbin");
  script_require_keys("installed_sw/Elasticsearch");

  exit(0);
}

include('vdf.inc');

# @tvdl-content
var vuln_data = {
  'metadata': {'spec_version': '1.0'},
  'requires': [
    {'scope': 'target', 'match': {'os': 'linux'}}
  ],
  'checks': [
    {
      'product': {'name': 'Elasticsearch', 'type': 'app'},
      'check_algorithm': 'default',
      'constraints': [
        {'min_version': '8.19.0', 'fixed_version': '8.19.20'},
        {'min_version': '9.0.0', 'fixed_version': '9.4.5'}
      ]
    }
  ]
};

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