Linux Distros Unpatched Vulnerability : CVE-2026-110952

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

include('compat.inc');

if (description)
{
  script_id(373866);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/29");

  script_cve_id("CVE-2026-110952");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-110952");

  script_set_attribute(attribute:"synopsis", value:
"The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be
patched.");
  script_set_attribute(attribute:"description", value:
"The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied
patch available.

  - A Kafka broker that authenticates clients with SASL/OAUTHBEARER using the bundled JWKS-backed validator
    always verifies the JWT signature, but two further checks are only performed when explicitly configured: -
    The issuer (iss) claim is verified only when sasl.oauthbearer.expected.issuer is set. When it is unset, a
    validly-signed token carrying the expected audience is accepted regardless of which issuer minted it. - An
    audience (aud) claim is required only when sasl.oauthbearer.expected.audience is set. When it is unset, a
    validly-signed token that omits the aud claim is accepted. (A token that carries an aud claim is still
    rejected when no expected audience is configured.) Both options default to unset and have been documented
    as optional (Importance LOW) since KIP-768 (3.1.0). Impact: The exposure is realizable mainly in
    deployments whose JWKS endpoint serves signing keys for more than one issuer (a multi-tenant identity
    provider, an aggregated/shared JWKS, or shared signing keys): a token minted for a different issuer, or a
    token lacking an audience, may be accepted to authenticate  potentially as a higher-privileged principal.
    In a single-issuer deployment where the provider controls the iss claim and issues audience-scoped tokens,
    exposure is limited. The signature trust anchor remains enforced in all cases. This is distinct from
    CVE-2026-33557 (acceptance of unsigned/unvalidated tokens); here the signature is validated and only the
    issuer/audience checks are not enforced by default. Mitigation (all affected versions, no upgrade
    required): Set both sasl.oauthbearer.expected.issuer (to your provider's exact iss value) and
    sasl.oauthbearer.expected.audience (to the audience(s) your brokers expect), per listener. Brokers that
    set these perform exact-match issuer/audience checks and are not affected. Both have been available since
    3.1.0. Resolution: - From Apache Kafka 4.4.0: a broker configured with a JWKS endpoint fails to start
    unless both sasl.oauthbearer.expected.issuer and sasl.oauthbearer.expected.audience are set (secure by
    default). Deployments that intentionally do not restrict the issuer and/or audience may opt out per axis
    with sasl.oauthbearer.allow.unverified.issuer=true and/or sasl.oauthbearer.allow.unverified.audience=true.
    (CVE-2026-110952)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-110952");
  script_set_attribute(attribute:"solution", value:
"There is no known solution at this time.");
  script_set_attribute(attribute:"agent", value:"unix");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:U/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-110952");

  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_unpatched", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/10/28");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/29");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:kafka");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

  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", "set_linux_os_id.nasl");
  script_require_keys("Host/cpu", "Host/local_checks_enabled", "global_settings/vendor_unpatched", "Host/OS/identifier");
  script_require_ports("Host/OS/Ubuntu Linux-18.04");

  exit(0);
}

if (!get_kb_item("global_settings/vendor_unpatched")) exit(0, "Unpatched Vulnerabilities Detection not active.");
if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (empty_or_null(get_one_kb_item("Host/Debian/dpkg-l"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "kafka"}
        ]
      }
    ]
  }
};

var distro_constraints_values = linux_unpatched::get_distro_constraints(distro_constraints_arr:distro_constraints_array);
if (empty_or_null(distro_constraints_values)) audit(AUDIT_HOST_NOT, 'affected');

var third_party_support = get_kb_item('Host/OS/extended-third-party');
if (!empty_or_null(third_party_support)) {
    var third_party_vendors = distro_constraints_values['third_party'];
    if (!empty_or_null(third_party_vendors)) {
        var vendor;
        foreach vendor (third_party_vendors) {
            if (vendor == third_party_support) exit(0, 'A third party management patch is available for this vulnerability from ' + vendor + '.\n');
        }
    }
}

var report = linux_unpatched::check_unpatched_constraints(distro_constraints_values:distro_constraints_values);

if (!empty_or_null(report))
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}