Pac4J JWT 4.x < 4.5.9 / 5.x < 5.7.9 / 6.x < 6.3.3 Authentication Bypass

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

include('compat.inc');

if (description)
{
  script_id(303207);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/03/23");

  script_cve_id("CVE-2026-29000");

  script_name(english:"Pac4J JWT 4.x < 4.5.9 / 5.x < 5.7.9 / 6.x < 6.3.3 Authentication Bypass");

  script_set_attribute(attribute:"synopsis", value:
"The remote host has a library that is affected by an authentication bypass vulnerability.");
  script_set_attribute(attribute:"description", value:
"The version of Pac4J JWT installed on the remote host is affected by an authentication bypass vulnerability.

  - pac4j-jwt versions prior to 4.5.9, 5.7.9, and 6.3.3 contain an authentication bypass vulnerability in
    JwtAuthenticator when processing encrypted JWTs that allows remote attackers to forge authentication
    tokens. Attackers who possess the server's RSA public key can create a JWE-wrapped PlainJWT with arbitrary
    subject and role claims, bypassing signature verification to authenticate as any user including
    administrators. (CVE-2026-29000)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported
version number.");
  # https://www.pac4j.org/blog/security-advisory-pac4j-jwt-jwtauthenticator.html
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?032b047b");
  script_set_attribute(attribute:"solution", value:
"Upgrade Pac4J JWT to version 4.5.9, 5.7.9, 6.3.3, or later based on the installed version branch.");
  script_set_attribute(attribute:"agent", value:"all");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-29000");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/03/04");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/03/02");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/03/20");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"asset_categories", value:"component");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:pac4j:pac4j-jwt");
  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("pac4j_jwt_installed.nbin");
  script_require_keys("installed_sw/Pac4J JWT");

  exit(0);
}

include('vdf.inc');

# @tvdl-content
var vuln_data = {
  'metadata': {'spec_version': '1.0'},
  'checks': [
    {
      'product': {'name': 'Pac4J JWT', 'type': 'app'},
      'check_algorithm': 'default',
      'constraints': [
        {'min_version': '4.0', 'fixed_version': '4.5.9'},
        {'min_version': '5.0', 'fixed_version': '5.7.9'},
        {'min_version': '6.0', 'fixed_version': '6.3.3'}
      ]
    }
  ]
};

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