libcurl SOCKS5 Heap Buffer Overflow Vulnerability (Oct 2023)

# SPDX-FileCopyrightText: 2025 Greenbone AG
# Some text descriptions might be excerpted from (a) referenced
# source(s), and are Copyright (C) by the respective right holder(s).
#
# SPDX-License-Identifier: GPL-2.0-only

CPE = "cpe:/a:haxx:libcurl";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.119059");
  script_version("2025-07-15T05:43:27+0000");
  script_tag(name:"last_modification", value:"2025-07-15 05:43:27 +0000 (Tue, 15 Jul 2025)");
  script_tag(name:"creation_date", value:"2025-07-14 12:41:11 +0000 (Mon, 14 Jul 2025)");
  script_tag(name:"cvss_base", value:"10.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:C/I:C/A:C");
  script_tag(name:"severity_vector", value:"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2023-10-25 13:24:03 +0000 (Wed, 25 Oct 2023)");
  script_cve_id("CVE-2023-38545");
  script_name("libcurl SOCKS5 Heap Buffer Overflow Vulnerability (Oct 2023)");
  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2025 Greenbone AG");
  script_family("Buffer overflow");
  script_dependencies("gb_libcurl_ssh_login_detect.nasl");
  script_mandatory_keys("libcurl/detected");

  script_xref(name:"URL", value:"https://curl.se/docs/CVE-2023-38545.html");

  script_tag(name:"summary", value:"libcurl is prone to a heap buffer overflow vulnerability in the
  SOCKS5 proxy handshake.");

  script_tag(name:"vuldetect", value:"Checks if a vulnerable version is present on the target host.");

  script_tag(name:"insight", value:"This flaw makes curl overflow a heap based buffer in the SOCKS5
  proxy handshake.

  When curl is asked to pass along the hostname to the SOCKS5 proxy to allow that to resolve the
  address instead of it getting done by curl itself, the maximum length that hostname can be is 255
  bytes.

  If the hostname is detected to be longer than 255 bytes, curl switches to local name resolving and
  instead passes on the resolved address only to the proxy. Due to a bug, the local variable that
  means 'let the host resolve the name' could get the wrong value during a slow SOCKS5 handshake,
  and contrary to the intention, copy the too long hostname to the target buffer instead of copying
  just the resolved address there.");

  script_tag(name:"affected", value:"libcurl versions starting from 7.69.0 and prior to 8.4.0.");

  script_tag(name:"solution", value:"Update to version 8.4.0 or later.");

  script_tag(name:"qod_type", value:"executable_version_unreliable");
  script_tag(name:"solution_type", value:"VendorFix");

  exit(0);
}

include("version_func.inc");
include("host_details.inc");

if( isnull( port = get_app_port( cpe:CPE ) ) )
  exit( 0 );

if( ! infos = get_app_version_and_location( cpe:CPE, port:port, exit_no_version:TRUE ) )
  exit( 0 );

version = infos["version"];
location = infos["location"];

if( version_in_range_exclusive( version:version, test_version_lo:"7.69.0", test_version_up:"8.4.0" ) ) {
  report = report_fixed_ver( installed_version:version, fixed_version:"8.4.0", install_path:location );
  security_message( port:port, data:report );
  exit( 0 );
}

exit( 99 );