Curl 7.10.6 < 8.19.0 Authentication Bypass

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

include('compat.inc');

if (description)
{
  script_id(302776);
  script_version("1.3");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/05/08");

  script_cve_id("CVE-2026-1965");
  script_xref(name:"IAVA", value:"2026-A-0237-S");

  script_name(english:"Curl 7.10.6 < 8.19.0 Authentication Bypass");

  script_set_attribute(attribute:"synopsis", value:
"The remote host has a program that is affected by an authentication bypass vulnerability");
  script_set_attribute(attribute:"description", value:
"The version of curl installed on the remote host is 7.10.6 prior to 8.19.0. It is, therefore, affected by 
an authentication bypass vulnerability:

  - libcurl can in some circumstances reuse the wrong connection when asked to do an Negotiate-authenticated 
    HTTP or HTTPS request. libcurl features a pool of recent connections so that subsequent requests can 
    reuse an existing connection to avoid overhead. When reusing a connection a range of criterion must 
    first be met. Due to a logical error in the code, a request that was issued by an application could 
    wrongfully reuse an existing connection to the same server that was authenticated using different 
    credentials. One underlying reason being that Negotiate sometimes authenticates *connections* and not 
    *requests*, contrary to how HTTP is designed to work. An application that allows Negotiate authentication 
    to a server (that responds wanting Negotiate) with `user1:password1` and then does another operation to 
    the same server also using Negotiate but with `user2:password2` (while the previous connection is still 
    alive) - the second request wrongly reused the same connection and since it then sees that the Negotiate 
    negotiation is already made, it just sends the request over that connection thinking it uses the user2 
    credentials when it is in fact still using the connection authenticated for user1... The set of 
    authentication methods to use is set with `CURLOPT_HTTPAUTH`. Applications can disable libcurl's reuse of 
    connections and thus mitigate this problem, by using one of the following libcurl options to alter how 
    connections are or are not reused: `CURLOPT_FRESH_CONNECT`, `CURLOPT_MAXCONNECTS` and 
    `CURLMOPT_MAX_HOST_CONNECTIONS` (if using the curl_multi API). (CVE-2026-1965)

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://curl.se/docs/CVE-2026-1965.html");
  script_set_attribute(attribute:"solution", value:
"Upgrade Curl to version 8.19.0 or later");
  script_set_attribute(attribute:"agent", value:"all");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/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-2026-1965");

  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:"2026/03/11");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/03/11");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/03/17");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"asset_categories", value:"component");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:haxx:curl");
  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("curl_win_installed.nbin", "curl_nix_installed.nbin");
  script_require_keys("installed_sw/Curl");

  exit(0);
}

include('vdf.inc');

# @tvdl-content
var vuln_data = {
  'metadata': {'spec_version': '1.0'},
  'checks': [
    {
      'product': {'name': 'Curl', 'type': 'app'},
      'check_algorithm': 'default',
      'constraints': [
        {'min_version': '7.10.6', 'fixed_version': '8.19.0'}
      ]
    }
  ]
};

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