Linux Distros Unpatched Vulnerability : CVE-2026-84784

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

include('compat.inc');

if (description)
{
  script_id(351242);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/30");

  script_cve_id("CVE-2026-84784");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-84784");

  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.

  - Issue summary: A malicious remote peer may flood the local QUIC stack with NEW_CONNECTION_ID frames by
    avoiding a limit check on how many connection IDs the remote QUIC stack can use. Impact summary: The local
    QUIC stack sends a RETIRE_CONN_ID frame for every NEW_CONNECTION_ID frame it receives. The RETIRE_CONN_ID
    frame is dispatched via the Control Frame Queue (CFQ). If the remote peer also withholds ACKs, then it can
    force the local stack to allocate ~400MB (depending on ACK delay). CWE: CWE-770: Allocation of Resources
    Without Limits or Throttling Description: RFC 9000 sections 5.1.1 and 5.1.2 [1] describe the mechanism by
    which a remote peer can notify the local QUIC stack to change the destination connection ID (a.k.a. CID)
    the local stack uses to identify the connection at the remote peer. Each CID is associated with a sequence
    number. The sequence number is transmitted in NEW_CONNECTION_ID and RETIRE_CONNECTION_ID frames to
    identify the CID which is being either associated with a connection or retired. The remote peer sends a
    NEW_CONNECTION_ID frame to let the local stack know a new CID is being associated with an existing
    connection. The NEW_CONNECTION_ID frame carries the new CID, its sequence number, and the retire-prior-to
    number. The retire-prior-to identifies existing CIDs that are to be retired. The local QUIC stack must
    send a RETIRE_CONNECTION_ID for every destination CID whose sequence number is less than retire-prior-to.
    The CID becomes retired after the local stack receives an ACK for its RETIRE_CONNECTION_ID frame. Although
    the OpenSSL QUIC stack supports at most one destination CID for every connection, it can be tricked into
    processing more than one RETIRE_CONNECTION_ID frame per connection. The OpenSSL QUIC stack currently
    retires the destination CID as soon as it receives the NEW_CONNECTION_ID, while in fact the destination
    CID must be retired after an ACK for the RETIRE_CONNECTION_ID frame is received. Correcting the flawed
    logic also fixes the backlog growth. [1] https://datatracker.ietf.org/doc/html/rfc9000#name-issuing-
    connection-ids FIPS impact: no The FIPS module is not affected as the QUIC implementation is outside of
    the OpenSSL FIPS module boundary. (CVE-2026-84784)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-84784");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-84784");
  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:L/AC:L/Au:N/C:N/I:N/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:U/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:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-84784");

  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:"2026/09/29");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/30");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:22.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:26.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:14.0");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:edk2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:edk2-hwe");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:nodejs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openssl");
  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/Debian Linux-14", "Host/OS/Ubuntu Linux-22.04", "Host/OS/Ubuntu Linux-26.04");

  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 = {
  "Debian Linux-14": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14",
        "pkgs": [
          {"reference": "libcrypto3-udeb"},
          {"reference": "libssl-dev"},
          {"reference": "libssl-doc"},
          {"reference": "libssl3-udeb"},
          {"reference": "libssl3t64"},
          {"reference": "openssl"},
          {"reference": "openssl-provider-fips"},
          {"reference": "openssl-provider-legacy"}
        ]
      }
    ]
  },
  "Ubuntu Linux-22.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "22.04",
        "pkgs": [
          {"reference": "nodejs"}
        ]
      }
    ]
  },
  "Ubuntu Linux-26.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "26.04",
        "pkgs": [
          {"reference": "efi-shell-aa64"},
          {"reference": "efi-shell-aa64-hwe"},
          {"reference": "efi-shell-loongarch64"},
          {"reference": "efi-shell-loongarch64-hwe"},
          {"reference": "efi-shell-riscv64"},
          {"reference": "efi-shell-riscv64-hwe"},
          {"reference": "efi-shell-x64"},
          {"reference": "efi-shell-x64-hwe"},
          {"reference": "ovmf"},
          {"reference": "ovmf-amdsev"},
          {"reference": "ovmf-amdsev-hwe"},
          {"reference": "ovmf-generic"},
          {"reference": "ovmf-generic-hwe"},
          {"reference": "ovmf-hwe"},
          {"reference": "ovmf-inteltdx"},
          {"reference": "ovmf-inteltdx-hwe"},
          {"reference": "ovmf-legacy"},
          {"reference": "ovmf-legacy-hwe"},
          {"reference": "qemu-efi-aarch64"},
          {"reference": "qemu-efi-aarch64-hwe"},
          {"reference": "qemu-efi-loongarch64"},
          {"reference": "qemu-efi-loongarch64-hwe"},
          {"reference": "qemu-efi-riscv64"},
          {"reference": "qemu-efi-riscv64-hwe"}
        ]
      }
    ]
  }
};

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');
}