Linux Distros Unpatched Vulnerability : CVE-2026-63073

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

include('compat.inc');

if (description)
{
  script_id(339521);
  script_version("1.4");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/28");

  script_cve_id("CVE-2026-63073");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-63073");

  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: OpenSSL CMP response validation passed an unexpected response sender distinguished name
    directly as the format string to `ERR_raise_data()`. Impact summary: A malicious or intercepted CMP
    endpoint can crash a CMP client that enforces an expected sender or uses a pinned server certificate whose
    subject becomes the default expected sender. CWE: CWE-134 (Use of Externally-Controlled Format String)
    Description: When validating a received CMP message, ossl_cmp_msg_check_update() converts the peer-
    supplied sender distinguished name with X509_NAME_oneline() and passes it directly as the format argument
    to ERR_raise_data(). Percent characters survive the conversion, so a sender DN such as CN=%s%n reaches
    BIO_vsnprintf() as an attacker-controlled format string with no matching variadic arguments. This path is
    only reached when the caller configures an expected sender or pins a server certificate, which is the
    normal configuration for a CMP client validating server responses. Since the attacker controls the format
    string but none of the variadic arguments, such specifiers as %s and %n dereference or write through
    unrelated stack contents and crash the client. The reliable consequence is a denial of service, when the
    response comes from a malicious or intercepted CMP endpoint. There is no controlled memory write,
    arbitrary-address read, or reliable path to remote code execution. FIPS impact: no No FIPS modules are
    affected by this issue, as the CMP protocol implementation is outside the OpenSSL FIPS module boundary.
    (CVE-2026-63073)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/cve/cve-2026-63073");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-63073");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-63073");
  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:P");
  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:H/I:H/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-2026-63073");

  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:"2026/08/25");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/25");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-: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:"cpe:/o:redhat:enterprise_linux:10");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:9");
  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:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:edk2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:edk2-aarch64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:edk2-ovmf");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:edk2-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:edk2-tools-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:openssl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:openssl-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:openssl-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:openssl-perl");
  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/Red Hat Enterprise Linux-10", "Host/OS/Red Hat Enterprise Linux-9", "Host/OS/Ubuntu Linux-16.04", "Host/OS/Ubuntu Linux-18.04", "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")) && empty_or_null(get_one_kb_item("Host/RedHat/rpm-list"))) 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-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "nodejs"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "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"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-10": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "10",
        "pkgs": [
          {"reference": "edk2"},
          {"reference": "edk2-aarch64"},
          {"reference": "edk2-ovmf"},
          {"reference": "edk2-tools"},
          {"reference": "edk2-tools-doc"},
          {"reference": "openssl"},
          {"reference": "openssl-devel"},
          {"reference": "openssl-libs"},
          {"reference": "openssl-perl"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-9": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "9",
        "pkgs": [
          {"reference": "openssl"},
          {"reference": "openssl-devel"},
          {"reference": "openssl-libs"},
          {"reference": "openssl-perl"}
        ]
      }
    ]
  }
};

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');
}