ISC BIND DoS Vulnerability (CVE-2025-40777) - Linux

# 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:isc:bind";

if (description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.154965");
  script_version("2025-07-18T05:44:10+0000");
  script_tag(name:"last_modification", value:"2025-07-18 05:44:10 +0000 (Fri, 18 Jul 2025)");
  script_tag(name:"creation_date", value:"2025-07-17 03:10:33 +0000 (Thu, 17 Jul 2025)");
  script_tag(name:"cvss_base", value:"7.8");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:N/I:N/A:C");
  script_tag(name:"severity_vector", value:"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2025-07-16 18:15:24 +0000 (Wed, 16 Jul 2025)");

  script_cve_id("CVE-2025-40777");

  script_tag(name:"qod_type", value:"remote_banner_unreliable");

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

  script_name("ISC BIND DoS Vulnerability (CVE-2025-40777) - Linux");

  script_category(ACT_GATHER_INFO);

  script_copyright("Copyright (C) 2025 Greenbone AG");
  script_family("Denial of Service");
  script_dependencies("gb_isc_bind_consolidation.nasl", "os_detection.nasl");
  script_mandatory_keys("isc/bind/detected", "Host/runs_unixoide");

  script_tag(name:"summary", value:"ISC BIND is prone to a denial of service (DoS)
  vulnerability.");

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

  script_tag(name:"insight", value:"If a named caching resolver is configured with
  serve-stale-enable yes, and with stale-answer-client-timeout set to 0 (the only allowable value
  other than disabled), and if the resolver, in the process of resolving a query, encounters a
  CNAME chain involving a specific combination of cached or authoritative records, the daemon will
  abort with an assertion failure.");

  script_tag(name:"impact", value:"If an attacker is able to make queries that yield the necessary
  combination of circumstances, they can force named to exit.");

  script_tag(name:"affected", value:"ISC BIND version 9.20.0 through 9.20.10, 9.21.0 through 9.21.9
  and 9.20.9-S1 through 9.20.10-S1.");

  script_tag(name:"solution", value:"Update to version 9.20.11, 9.21.10, 9.20.11-S1 or later.");

  script_xref(name:"URL", value:"https://kb.isc.org/docs/cve-2025-40777");

  exit(0);
}

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

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

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

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

if (version =~ "^9\.[0-9]+\.[0-9]+s[0-9]") {
  if (version_in_range(version: version, test_version: "9.20.9s1", test_version2: "9.20.10s1")) {
    report = report_fixed_ver(installed_version: version, fixed_version: "9.20.11-S1", install_path: location);
    security_message(port: port, data: report, proto: proto);
    exit(0);
  }
} else {
  if (version_in_range(version: version, test_version: "9.20.0", test_version2: "9.20.10")) {
    report = report_fixed_ver(installed_version: version, fixed_version: "9.20.11", install_path: location);
    security_message(port: port, data: report, proto: proto);
    exit(0);
  }

  if (version_in_range(version: version, test_version: "9.21.0", test_version2: "9.21.9")) {
    report = report_fixed_ver(installed_version: version, fixed_version: "9.21.10", install_path: location);
    security_message(port: port, data: report, proto: proto);
    exit(0);
  }
}

exit(99);