RabbitMQ 4.2.x < 4.2.4 MQTT Topic Authorization Bypass

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

include('compat.inc');

if (description)
{
  script_id(327579);
  script_version("1.3");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/20");

  script_cve_id("CVE-2026-44838");
  script_xref(name:"IAVA", value:"2026-A-0683");

  script_name(english:"RabbitMQ 4.2.x < 4.2.4 MQTT Topic Authorization Bypass");

  script_set_attribute(attribute:"synopsis", value:
"The RabbitMQ installed on the remote host is affected by a vulnerability.");
  script_set_attribute(attribute:"description", value:
"The version of RabbitMQ installed on the remote host is 4.2.x prior to 4.2.4. It is, therefore, affected by an
authorization bypass vulnerability:

  - RabbitMQ's MQTT plugin allows for topic-level authorization using regular expressions with variable substitution.
    However, the client_id is provided by the user in the MQTT CONNECT packet and is inserted into the regex pattern
    without escaping special regex characters. This flaw enables an authenticated MQTT user to inject regex operators
    to bypass authorization. (CVE-2026-44838)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  # https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-x866-xp2g-cx8v
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?053086c7");
  script_set_attribute(attribute:"solution", value:
"Upgrade to RabbitMQ version 4.2.4 or later.");
  script_set_attribute(attribute:"agent", value:"all");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/C:C/I:C/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:L/UI:N/S:U/C:H/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:H/SI:H/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:U");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-44838");

  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:"2026/05/27");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/05/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/17");

  script_set_attribute(attribute:"potential_vulnerability", value:"true");
  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:pivotal_software:rabbitmq");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:vmware:rabbitmq");
  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:"Misc.");

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

  script_dependencies("rabbitmq_server_nix_installed.nbin", "vmware_rabbitmq_win_installed.nbin");
  script_require_keys("installed_sw/RabbitMQ", "Settings/ParanoidReport");

  exit(0);
}
include('vdf.inc');

# Not checking if MQTT plugin is enabled
if (report_paranoia < 2) audit(AUDIT_PARANOID);

# @tvdl-content
var vuln_data = {
  'metadata': {'spec_version': '1.0'},
  'requires': [
    {'scope': 'target', 'match': {'paranoia': true}}
  ],
  'checks': [
    {
      'product': {'name': 'RabbitMQ', 'type': 'app'},
      'check_algorithm': 'default',
      'constraints': [
        {'min_version': '4.2.0', 'fixed_version': '4.2.4'}
      ]
    }
  ]
};

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