Python Library Tornado < 6.5.8 DoS (CVE-2026-82397)

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

include('compat.inc');

if (description)
{
  script_id(344487);
  script_version("1.3");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/11");

  script_cve_id("CVE-2026-82397");
  script_xref(name:"IAVB", value:"2026-B-0248");

  script_name(english:"Python Library Tornado < 6.5.8 DoS (CVE-2026-82397)");

  script_set_attribute(attribute:"synopsis", value:
"A Python library installed on the remote host is affected by a denial of service vulnerability.");
  script_set_attribute(attribute:"description", value:
"The version of the Tornado Python package installed on the remote host is prior to 6.5.8. It is, therefore,
affected by a denial of service vulnerability:

  - Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses
    application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without
    passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch
    through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an unauthenticated
    request body containing millions of separator-delimited fields can synchronously stall the single-threaded
    event loop and delay every connection. The body is bounded only by max_buffer_size, which defaults to
    104857600 bytes. This issue is fixed in version 6.5.8. (CVE-2026-82397)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  # https://github.com/tornadoweb/tornado/security/advisories/GHSA-mpf4-983q-p7j4
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?bd977304");
  script_set_attribute(attribute:"see_also", value:"https://github.com/tornadoweb/tornado/releases/tag/v6.5.8");
  script_set_attribute(attribute:"solution", value:
"Upgrade to Tornado version 6.5.8 or later.");
  script_set_attribute(attribute:"agent", value:"all");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/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:L/PR:N/UI:N/S:U/C:N/I:N/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-2026-82397");

  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:"2026/08/31");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/06");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/10");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"asset_categories", value:"component");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:tornadoweb:tornado");
  script_set_attribute(attribute:"thorough_tests", value:"true");
  script_set_attribute(attribute:"stig_severity", value:"I");
  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("python_packages_installed_nix.nbin", "python_packages_win_installed.nbin");
  script_require_ports("Host/nix/Python/Packages/Enumerated", "Host/win/Python/Packages/Enumerated");

  exit(0);
}

include('python.inc');

var pkg = 'Tornado';

var libs = python::get_package_info(pkg_name:pkg, cpe:"cpe:/a:tornadoweb:tornado");

if (empty_or_null(libs))
  audit(AUDIT_NOT_INST, pkg);

vcf::check_all_backporting(app_info:libs);

var constraints = [
  {'fixed_version': '6.5.8'}
];

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