ISC BIND 9.18.0 < 9.20.29 / 9.18.11-S1 < 9.20.29-S1 / 9.20.0 < 9.20.29 / 9.20.9-S1 < 9.20.29-S1 / 9.21.0 < 9.21.26 Multiple Vulnerabilities

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

include('compat.inc');

if (description)
{
  script_id(347971);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/18");

  script_cve_id("CVE-2026-81563", "CVE-2026-81736");
  script_xref(name:"IAVA", value:"2026-A-1029");

  script_name(english:"ISC BIND 9.18.0 < 9.20.29 / 9.18.11-S1 < 9.20.29-S1 / 9.20.0 < 9.20.29 / 9.20.9-S1 < 9.20.29-S1 / 9.21.0 < 9.21.26 Multiple Vulnerabilities");

  script_set_attribute(attribute:"synopsis", value:
"The remote name server is affected by multiple vulnerabilities.");
  script_set_attribute(attribute:"description", value:
"The version of ISC BIND running on the remote host is 9.18.0 through 9.18.50, 9.20.0 through 9.20.27, or 9.21.0
through 9.21.25. Supported Preview Edition releases 9.18.11-S1 through 9.18.50-S1 and 9.20.9-S1 through 9.20.27-S1 are
also affected. It is, therefore, affected by multiple vulnerabilities :

  - A BIND resolver encountering an SVCB/HTTPS AliasMode record referencing 14 or more SVCB/HTTPS ServiceMode
    records may fail to properly deallocate internal resources. If this happens repeatedly, resource exhaustion
    will eventually prevent the resolver from performing new recursive lookups. (CVE-2026-81563)

  - If a BIND resolver has cached a tree of SVCB/HTTPS AliasMode records, and is then queried for the root of
    that tree, the resolver will spend disproportionate CPU time constructing the response. (CVE-2026-81736)

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://kb.isc.org/docs/cve-2026-81563");
  script_set_attribute(attribute:"see_also", value:"https://kb.isc.org/docs/cve-2026-81736");
  script_set_attribute(attribute:"see_also", value:"https://kb.isc.org/docs/aa-00913");
  script_set_attribute(attribute:"solution", value:
"Upgrade to ISC BIND version 9.20.29 / 9.20.29-S1 / 9.21.26 or later. Note that the 9.18 branch is end of life and no
fix is available for it; migrate to a supported branch.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-81563");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/09/16");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/16");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/18");

  script_set_attribute(attribute:"potential_vulnerability", value:"true");
  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:isc:bind");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"DNS");

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

  script_dependencies("bind_version.nasl");
  script_require_keys("bind/version", "Settings/ParanoidReport");

  exit(0);
}

include('vcf.inc');
include('vcf_extras.inc');

vcf::bind::initialize();

var app_info = vcf::get_app_info(app:'BIND', port:53, kb_ver:'bind/version', service:TRUE, proto:'UDP');

if (report_paranoia < 2) audit(AUDIT_PARANOID);

var constraints = [
  { 'min_version' : '9.18.0', 'max_version' : '9.18.50', 'fixed_display' : '9.20.29' },
  { 'min_version' : '9.18.11-S1', 'max_version' : '9.18.50-S1', 'fixed_display' : '9.20.29-S1' },
  { 'min_version' : '9.20.0', 'max_version' : '9.20.27', 'fixed_display' : '9.20.29' },
  { 'min_version' : '9.20.9-S1', 'max_version' : '9.20.27-S1', 'fixed_display' : '9.20.29-S1' },
  { 'min_version' : '9.21.0', 'max_version' : '9.21.25', 'fixed_display' : '9.21.26' }
];
constraints = vcf::bind::filter_constraints(constraints:constraints, version:app_info.version);

vcf::check_version_and_report(
    app_info:app_info,
    constraints:constraints,
    severity:SECURITY_HOLE
);