AlmaLinux 9.6 [TuxCare] Security Update: avahi / avahi-autoipd / avahi-compat-howl / avahi-compat-howl-devel / etc Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1786533280)

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

include('compat.inc');

if (description)
{
  script_id(352803);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/01");

  script_cve_id("CVE-2025-59529", "CVE-2025-68276", "CVE-2026-34933");
  script_xref(name:"CLSA", value:"2026:1786533280");

  script_name(english:"AlmaLinux 9.6 [TuxCare] Security Update: avahi / avahi-autoipd / avahi-compat-howl / avahi-compat-howl-devel / etc Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1786533280)");

  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-2026:1786533280 advisory.

  - Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol
    suite. In versions up to and including 0.9-rc2, the simple protocol server ignores the documented client
    limit and accepts unlimited connections, allowing for easy local DoS. Although `CLIENTS_MAX` is defined,
    `server_work()` unconditionally `accept()`s and `client_new()` always appends the new client and
    increments `n_clients`. There is no check against the limit. When client cannot be accepted as a result of
    maximal socket number of avahi-daemon, it logs unconditionally error per each connection. Unprivileged
    local users can exhaust daemon memory and file descriptors, causing a denial of service system-wide for
    mDNS/DNS-SD. Exhausting local file descriptors causes increased system load caused by logging errors of
    each of request. Overloading prevents glibc calls using nss-mdns plugins to resolve `*.local.` names and
    link-local addresses. As of time of publication, no known patched versions are available, but a candidate
    fix is available in pull request 808, and some workarounds are available. Simple clients are offered for
    nss-mdns package functionality. It is not possible to disable the unix socket `/run/avahi-daemon/socket`,
    but resolution requests received via DBus are not affected directly. Tools avahi-resolve, avahi-resolve-
    address and avahi-resolve-host-name are not affected, they use DBus interface. It is possible to change
    permissions of unix socket after avahi-daemon is started. But avahi-daemon does not provide any
    configuration for it. Additional access restrictions like SELinux can also prevent unwanted tools to
    access the socket and keep resolution working for trusted users. (CVE-2025-59529)

  - Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol
    suite. In 0.9-rc2 and earlier, an unprivileged local users can crash avahi-daemon (with wide-area
    disabled) by creating record browsers with the AVAHI_LOOKUP_USE_WIDE_AREA flag set via D-Bus. This can be
    done by either calling the RecordBrowserNew method directly or creating hostname/address/service
    resolvers/browsers that create those browsers internally themselves. (CVE-2025-68276)

  - Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol
    suite. Prior to version 0.9-rc4, any unprivileged local user can crash avahi-daemon by sending a single
    D-Bus method call with conflicting publish flags. This issue has been patched in version 0.9-rc4.
    (CVE-2026-34933)

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_1786533280.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?436e070c");
  script_set_attribute(attribute:"see_also", value:"https://cve.tuxcare.com/els/releases/CLSA-2026:1786533280");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages based on the guidance in TuxCare advisory ALMALINUX9.6:CLSA-2026:1786533280.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-34933");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_set_attribute(attribute:"vendor_severity", value:"Moderate");

  script_set_attribute(attribute:"vuln_publication_date", value:"2025/12/18");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/12");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/30");

  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':'avahi-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'i686', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-autoipd-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-compat-howl-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'i686', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-compat-howl-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-compat-howl-devel-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'i686', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-compat-howl-devel-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-compat-libdns_sd-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'i686', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-compat-libdns_sd-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-compat-libdns_sd-devel-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'i686', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-compat-libdns_sd-devel-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-devel-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'i686', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-devel-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-dnsconfd-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-glib-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'i686', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-glib-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-glib-devel-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'i686', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-glib-devel-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-gobject-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'i686', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-gobject-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-gobject-devel-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'i686', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-gobject-devel-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-libs-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'i686', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-libs-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-tools-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-ui-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-ui-devel-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-ui-gtk3-0.8-22.el9_6.1.tuxcare.els2', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'avahi-ui-tools-0.8-22.el9_6.1.tuxcare.els2', '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_WARNING,
      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, 'avahi / avahi-autoipd / avahi-compat-howl / avahi-compat-howl-devel / etc');
}