Amazon Linux 2 : unbound (ALASUNBOUND-1.17-2026-010)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2 Security Advisory ALASUNBOUND-1.17-2026-010.
##

include('compat.inc');

if (description)
{
  script_id(347944);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/18");

  script_cve_id("CVE-2026-81642");

  script_name(english:"Amazon Linux 2 : unbound (ALASUNBOUND-1.17-2026-010)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Amazon Linux 2 host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The version of unbound installed on the remote host is prior to 1.17.0-2. It is, therefore, affected by a vulnerability
as referenced in the ALAS2UNBOUND-1.17-2026-010 advisory.

    In NLnet Labs Unbound up to and including 1.26.0, a vulnerability was found in the DNSSEC validator that
    enables denial of service and possible remote code execution as a result of digesting DNSKEYs. A DNSKEY
    with an owner compression pointer to its own RDATA can overflow the digest buffer. Remote code execution
    is possible through attacker controlled data. An adversary can exploit the vulnerability by controlling a
    malicious zone and querying a vulnerable Unbound. (CVE-2026-81642)

Tenable has extracted the preceding description block directly from the tested product security advisory.

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://alas.aws.amazon.com//AL2/ALAS2UNBOUND-1.17-2026-010.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/faqs.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-81642.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update unbound' or
  or 'yum update --advisory ALAS2UNBOUND-1.17-2026-010' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/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:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H");
  script_set_attribute(attribute:"cvss4_supplemental", value:"CVSS:4.0/U:Red");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:U");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-81642");

  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:"2026/09/16");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/17");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/18");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python2-unbound");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python3-unbound");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:unbound");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:unbound-anchor");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:unbound-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:unbound-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:unbound-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:unbound-utils");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Amazon Linux Local Security Checks");

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

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/AmazonLinux/release", "Host/AmazonLinux/rpm-list");

  exit(0);
}

include("rpm2.inc");

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);

var alas_release = get_kb_item("Host/AmazonLinux/release");
if (isnull(alas_release) || !strlen(alas_release)) audit(AUDIT_OS_NOT, "Amazon Linux");
var os_ver = pregmatch(pattern: "^AL(A|\d+|-\d+)", string:alas_release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Amazon Linux");
os_ver = os_ver[1];
if (os_ver != "2")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux 2", "Amazon Linux " + os_ver);
}

if (!get_kb_item("Host/AmazonLinux/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);

var REPOS_FOUND = TRUE;
var extras_list = get_kb_item("Host/AmazonLinux/extras_label_list");
if (isnull(extras_list)) REPOS_FOUND = FALSE;
var repository = '"amzn2extra-unbound-1.17"';
if (REPOS_FOUND && (repository >!< extras_list)) exit(0, AFFECTED_REPO_NOT_ENABLED);

var pkgs = [
    {'reference':'python2-unbound-1.17.0-2.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'python2-unbound-1.17.0-2.amzn2.0.13', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'python3-unbound-1.17.0-2.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'python3-unbound-1.17.0-2.amzn2.0.13', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'unbound-1.17.0-2.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'unbound-1.17.0-2.amzn2.0.13', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'unbound-anchor-1.17.0-2.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'unbound-anchor-1.17.0-2.amzn2.0.13', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'unbound-debuginfo-1.17.0-2.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'unbound-debuginfo-1.17.0-2.amzn2.0.13', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'unbound-devel-1.17.0-2.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'unbound-devel-1.17.0-2.amzn2.0.13', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'unbound-libs-1.17.0-2.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'unbound-libs-1.17.0-2.amzn2.0.13', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'unbound-utils-1.17.0-2.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'},
    {'reference':'unbound-utils-1.17.0-2.amzn2.0.13', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'unbound-1.17'}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var reference = NULL;
  var _release = NULL;
  var sp = NULL;
  var _cpu = NULL;
  var el_string = NULL;
  var rpm_spec_vers_cmp = NULL;
  var epoch = NULL;
  var allowmaj = NULL;
  var exists_check = NULL;
  var cves = NULL;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) _release = package_array['release'];
  if (!empty_or_null(package_array['sp'])) sp = package_array['sp'];
  if (!empty_or_null(package_array['cpu'])) _cpu = package_array['cpu'];
  if (!empty_or_null(package_array['el_string'])) el_string = package_array['el_string'];
  if (!empty_or_null(package_array['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = package_array['rpm_spec_vers_cmp'];
  if (!empty_or_null(package_array['epoch'])) epoch = package_array['epoch'];
  if (!empty_or_null(package_array['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (!empty_or_null(package_array['exists_check'])) exists_check = package_array['exists_check'];
  if (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  if (reference && _release && (!exists_check || rpm_exists(release:_release, rpm:exists_check))) {
    if (rpm_check(release:_release, sp:sp, cpu:_cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj, cves:cves)) flag++;
  }
}

if (flag)
{
  var extra = rpm_report_get();
  if (!REPOS_FOUND) extra = rpm_report_get() + report_repo_caveat();
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : extra
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "python2-unbound / python3-unbound / unbound / etc");
}