CentOS Linux 7 [TuxCare] Security Update: unbound / unbound-devel / unbound-libs / unbound-python Multiple Vulnerabilities (CENTOS7:CLSA-2026:1779978016)

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

include('compat.inc');

if (description)
{
  script_id(360317);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/01");

  script_cve_id("CVE-2026-41292", "CVE-2026-42959", "CVE-2026-42960");
  script_xref(name:"CLSA", value:"2026:1779978016");

  script_name(english:"CentOS Linux 7 [TuxCare] Security Update: unbound / unbound-devel / unbound-libs / unbound-python Multiple Vulnerabilities (CENTOS7:CLSA-2026:1779978016)");

  script_set_attribute(attribute:"synopsis", value:
"The CentOS Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The CentOS Linux 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the
TuxCare CENTOS7:CLSA-2026:1779978016 advisory.

  - NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to a degradation of service attack
    related to parsing long lists of incoming EDNS options. An adversary sending queries with too many EDNS
    options can hold Unbound threads hostage while they are parsing and creating internal data structures for
    the options. Coordinated attacks can result in degradation and/or denial of service. Unbound 1.25.1
    contains a patch with a fix to limit acceptable incoming EDNS options (100). (CVE-2026-41292)

  - NLnet Labs Unbound up to and including version 1.25.0 has a denial of service vulnerability in the DNSSEC
    validator that can lead to a crash given malicious upstream replies. When Unbound constructs chase-reply
    messages for validation, the code uses the wrong counter to calculate write offsets for ADDITIONAL section
    rrsets. DNAME duplication could increase the ANSWER section count and authority filtering could decrease
    the AUTHORITY section count and create an uninitialized array slot. Combining these two, the validator
    later dereferences this uninitialized pointer, causing an immediate process crash. An adversary
    controlling a DNSSEC-signed domain can trigger this bug with a single query by configuring a DNAME chain
    with unsigned CNAMEs and a response containing unsigned AUTHORITY records alongside signed ADDITIONAL glue
    records. Unbound 1.25.1 contains a patch with a fix to use the proper counters to calculate the write
    offsets. (CVE-2026-42959)

  - NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records
    for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be
    used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply
    (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound's cache. A malicious actor
    can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by
    address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or
    fragmentation attacks. Unbound would then accept the relative address records in the additional section
    and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the
    delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the
    additional section if they are not explicitly relevant only to authority NS records, mitigating the
    possible poison effect. This is a complement fix to CVE-2025-11411. (CVE-2026-42960)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  # https://security.tuxcare.com/csaf/v2/els_os/centos7els/advisories/2026/clsa-2026_1779978016.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?25c6061b");
  script_set_attribute(attribute:"see_also", value:"https://cve.tuxcare.com/els/releases/CLSA-2026:1779978016");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages based on the guidance in TuxCare advisory CENTOS7:CLSA-2026:1779978016.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:C/A:C");
  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:C/C:N/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:N/VI:N/VA:H/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:U");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-42960");
  script_set_attribute(attribute:"cvss4_score_source", value:"CVE-2026-42959");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_set_attribute(attribute:"vendor_severity", value:"Critical");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/05/20");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/05/28");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/01");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"CentOS 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_info2.nasl");
  script_require_keys("Host/OS/extended-third-party", "Host/local_checks_enabled", "Host/CentOS/release", "Host/CentOS/rpm-list");

  exit(0);
}
include('rpm2.inc');

var third_party_support = get_kb_item('Host/OS/extended-third-party');
if (empty_or_null(third_party_support) || third_party_support != 'TuxCare') exit(0, 'TuxCare support not enabled.');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_product = get_kb_item('installed_os/local/SSH/0/product');
if (isnull(os_product) || 'CentOS Linux' >!< os_product) audit(AUDIT_OS_NOT, 'CentOS Linux');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'CentOS Linux');
if (! preg(pattern:"^7([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'CentOS Linux 7', 'CentOS Linux ' + os_version);

if (!get_kb_item('Host/CentOS/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if (cpu !~ "^i[3-6]86$" && 'x86_64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'CentOS Linux', cpu);


var constraints = [
  {
    'release': '7',
    'pkgs': [
      {'reference':'unbound-1.6.6-5.el7_8.tuxcare.els6', 'cpu':'x86_64', 'el_string':'el7_8', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'unbound-devel-1.6.6-5.el7_8.tuxcare.els6', 'cpu':'i686', 'el_string':'el7_8', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'unbound-devel-1.6.6-5.el7_8.tuxcare.els6', 'cpu':'x86_64', 'el_string':'el7_8', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'unbound-libs-1.6.6-5.el7_8.tuxcare.els6', 'cpu':'i686', 'el_string':'el7_8', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'unbound-libs-1.6.6-5.el7_8.tuxcare.els6', 'cpu':'x86_64', 'el_string':'el7_8', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'unbound-python-1.6.6-5.el7_8.tuxcare.els6', 'cpu':'x86_64', 'el_string':'el7_8', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

var os_release = get_one_kb_item('installed_os/local/SSH/0/release');
var os_sp = get_one_kb_item('Host/*/minor_release');

var flag = 0;
var reference;
var sp;
var _cpu;
var el_string;
var rpm_spec_vers_cmp;
var epoch;
var allowmaj;
var exists_check;
var cves;
foreach var constraint ( constraints ) {
  # Check that the target release is equal to the affected release
  if (!empty_or_null(constraint['release'])){
    if (constraint['release'] != os_release) continue;
  }
  if (!empty_or_null(constraint['sp'])){
    if (constraint['sp'] != os_sp) continue;
  }
  foreach var pkg ( constraint['pkgs'] ) {
    reference = NULL;
    sp = NULL;
    _cpu = NULL;
    el_string = NULL;
    rpm_spec_vers_cmp = NULL;
    epoch = NULL;
    allowmaj = NULL;
    exists_check = NULL;
    cves = NULL;
    if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
    if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
    if (!empty_or_null(pkg['cpu'])) _cpu = pkg['cpu'];
    if (!empty_or_null(pkg['el_string'])) el_string = pkg['el_string'];
    if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
    if (!empty_or_null(pkg['epoch'])) epoch = pkg['epoch'];
    if (!empty_or_null(pkg['allowmaj'])) allowmaj = pkg['allowmaj'];
    if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
    if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
    if (reference &&
        ## (no known rpm to check OR known rpm_exists)
        (!exists_check || rpm_exists(rpm:exists_check)) &&
        rpm_check(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)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'unbound / unbound-devel / unbound-libs / unbound-python');
}