AlmaLinux 9.6 [TuxCare] Security Update: python3-unbound / unbound / unbound-devel / unbound-dracut / etc Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1780068958)

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

include('compat.inc');

if (description)
{
  script_id(360147);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/01");

  script_cve_id(
    "CVE-2026-32792",
    "CVE-2026-41292",
    "CVE-2026-42944",
    "CVE-2026-42959",
    "CVE-2026-44390",
    "CVE-2026-44608"
  );
  script_xref(name:"CLSA", value:"2026:1780068958");

  script_name(english:"AlmaLinux 9.6 [TuxCare] Security Update: python3-unbound / unbound / unbound-devel / unbound-dracut / etc Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1780068958)");

  script_set_attribute(attribute:"synopsis", value:
"The AlmaLinux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The AlmaLinux 9.6 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare
ALMALINUX9.6:CLSA-2026:1780068958 advisory.

  - NLnet Labs Unbound 1.6.2 up to and including version 1.25.0 has a denial of service vulnerability when
    compiled with DNSCrypt support ('--enable-dnscrypt'). A bad DNSCrypt query could underflow Unbound's
    DNSCrypt packet reading procedure that may lead to heap overflow. A malicious actor can exploit the
    vulnerability with a single bad DNSCrypt query that its decrypted plaintext consists entirely of '0x00'
    bytes and does not contain the expected '0x80' marker. Unbound would then start reading more bytes than
    necessary until it finds a non-'0x00' byte. Based on the underlying memory allocator and the memory
    layout, it could lead to heap overflow while reading followed by a crash. Likelihood of a crash is low,
    since it relies heavily on the underlying memory allocator and the memory layout. If the heap overflow
    does not happen, Unbound's later packet checks will deny the packet. Unbound 1.25.1 contains a patch with
    a fix to bound reading in the given buffer space. (CVE-2026-32792)

  - 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 1.14.0 up to and including version 1.25.0 has a vulnerability that results in heap
    overflow when encoding multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options in the reply
    packet. The relevant options ('nsid', 'answer-cookie', 'pad-responses' (default)) need to be enabled for
    the vulnerability to be exploited. An adversary who can query Unbound can exploit the vulnerability by
    attaching multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options to the query. A flaw in the
    size calculation of the EDNS field truncates the correct value which allows the encoder to overflow the
    available space when writing. Those two combined lead to a heap overflow write of Unbound controlled data
    and eventually a crash. Unbound 1.25.1 contains a patch with a fix to de-duplicate the EDNS options and a
    fix to prevent truncation of the EDNS field size calculation. (CVE-2026-42944)

  - 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 has a vulnerability when handling replies with very
    large RRsets that Unbound needs to perform name compression for. Malicious upstream responses with very
    large RRsets with records that don't share a suffix above the root can cause Unbound to spend a
    considerable time applying name compression to downstream replies. This can lead to degraded performance
    and eventually denial of service in well orchestrated attacks. An adversary can exploit the vulnerability
    by querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before
    Unbound replies to the query it will try to apply name compression which was an unbounded operation that
    could lock the CPU until the whole packet was complete. A compression limit was introduced in 1.21.1 for
    this but it didn't account for the case where records would not share any suffix above the root. That
    causes Unbound to go in a different code path because of the compression tree lookup failure and
    eventually not increment the compression counter for those operations. Unbound 1.25.1 contains a patch
    with a fix that increments the compression counter regardless of the compression tree lookup. This is a
    complement fix to CVE-2024-8508. (CVE-2026-44390)

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/tuxcare9.6esu/advisories/2026/clsa-2026_1780068958.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?bc6369c6");
  script_set_attribute(attribute:"see_also", value:"https://cve.tuxcare.com/els/releases/CLSA-2026:1780068958");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages based on the guidance in TuxCare advisory ALMALINUX9.6:CLSA-2026:1780068958.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/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:U/C:N/I:N/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-2026-42959");

  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:"Important");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/05/20");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/05/29");
  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:"Alma 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_info2.nasl");
  script_require_keys("Host/OS/extended-third-party", "Host/local_checks_enabled", "Host/AlmaLinux/release", "Host/AlmaLinux/rpm-list", "Host/cpu");

  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) || 'AlmaLinux' >!< os_product) audit(AUDIT_OS_NOT, 'AlmaLinux');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'AlmaLinux');
if (! preg(pattern:"^9.6([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'AlmaLinux 9.6', 'AlmaLinux ' + os_version);

if (!get_kb_item('Host/AlmaLinux/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, 'AlmaLinux', cpu);


var constraints = [
  {
    'release': '9',
    'sp': '6',
    'pkgs': [
      {'reference':'python3-unbound-1.16.2-19.el9_6.1.tuxcare.els5', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'unbound-1.16.2-19.el9_6.1.tuxcare.els5', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'unbound-devel-1.16.2-19.el9_6.1.tuxcare.els5', 'sp':'6', 'cpu':'i686', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'unbound-devel-1.16.2-19.el9_6.1.tuxcare.els5', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'unbound-dracut-1.16.2-19.el9_6.1.tuxcare.els5', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'unbound-libs-1.16.2-19.el9_6.1.tuxcare.els5', 'sp':'6', 'cpu':'i686', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'unbound-libs-1.16.2-19.el9_6.1.tuxcare.els5', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', '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, 'python3-unbound / unbound / unbound-devel / unbound-dracut / etc');
}