Linux Distros Unpatched Vulnerability : CVE-2026-6409

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

include('compat.inc');

if (description)
{
  script_id(306841);
  script_version("1.4");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/05/22");

  script_cve_id("CVE-2026-6409");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-6409");

  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 Denial of Service (DoS) vulnerability exists in the Protobuf PHP library during the parsing of untrusted
    input. Maliciously structured messagesspecifically those containing negative varints or deep
    recursioncan be used to crash the application, impacting service availability. (CVE-2026-6409)

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-2026-6409");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-6409");
  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:N/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:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/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-2026-6409");

  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:"2026/04/16");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/04/16");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:14.04:-:lts");
  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:20.04:-:lts");
  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:24.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:25.10");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:11.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:12.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:13.0");
  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:protobuf");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:protobuf");
  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-11", "Host/OS/Debian Linux-12", "Host/OS/Debian Linux-13", "Host/OS/Debian Linux-14", "Host/OS/Ubuntu Linux-14.04", "Host/OS/Ubuntu Linux-16.04", "Host/OS/Ubuntu Linux-18.04", "Host/OS/Ubuntu Linux-20.04", "Host/OS/Ubuntu Linux-22.04", "Host/OS/Ubuntu Linux-24.04", "Host/OS/Ubuntu Linux-25.10");

  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-12": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "12",
        "pkgs": [
          {"reference": "elpa-protobuf-mode"},
          {"reference": "libprotobuf-dev"},
          {"reference": "libprotobuf-java"},
          {"reference": "libprotobuf-lite32"},
          {"reference": "libprotobuf32"},
          {"reference": "libprotoc-dev"},
          {"reference": "libprotoc32"},
          {"reference": "php-google-protobuf"},
          {"reference": "protobuf-compiler"},
          {"reference": "python3-protobuf"},
          {"reference": "ruby-google-protobuf"}
        ]
      }
    ]
  },
  "Debian Linux-11": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "11",
        "pkgs": [
          {"reference": "elpa-protobuf-mode"},
          {"reference": "libprotobuf-dev"},
          {"reference": "libprotobuf-java"},
          {"reference": "libprotobuf-lite23"},
          {"reference": "libprotobuf23"},
          {"reference": "libprotoc-dev"},
          {"reference": "libprotoc23"},
          {"reference": "protobuf-compiler"},
          {"reference": "python3-protobuf"},
          {"reference": "ruby-google-protobuf"}
        ]
      }
    ]
  },
  "Ubuntu Linux-22.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "22.04",
        "pkgs": [
          {"reference": "elpa-protobuf-mode"},
          {"reference": "libprotobuf-dev"},
          {"reference": "libprotobuf-java"},
          {"reference": "libprotobuf-lite23"},
          {"reference": "libprotobuf23"},
          {"reference": "libprotoc-dev"},
          {"reference": "libprotoc23"},
          {"reference": "protobuf-compiler"},
          {"reference": "python3-protobuf"},
          {"reference": "ruby-google-protobuf"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "elpa-protobuf-mode"},
          {"reference": "libprotobuf-dev"},
          {"reference": "libprotobuf-java"},
          {"reference": "libprotobuf-lite32t64"},
          {"reference": "libprotobuf32t64"},
          {"reference": "libprotoc-dev"},
          {"reference": "libprotoc32t64"},
          {"reference": "php-google-protobuf"},
          {"reference": "protobuf-compiler"},
          {"reference": "python3-protobuf"},
          {"reference": "ruby-google-protobuf"}
        ]
      }
    ]
  },
  "Debian Linux-14": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14",
        "pkgs": [
          {"reference": "elpa-protobuf-mode"},
          {"reference": "libprotobuf-dev"},
          {"reference": "libprotobuf-java"},
          {"reference": "libprotobuf-lite32t64"},
          {"reference": "libprotobuf32t64"},
          {"reference": "libprotoc-dev"},
          {"reference": "libprotoc32t64"},
          {"reference": "php-google-protobuf"},
          {"reference": "protobuf-compiler"},
          {"reference": "python3-protobuf"},
          {"reference": "ruby-google-protobuf"}
        ]
      }
    ]
  },
  "Ubuntu Linux-24.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "24.04",
        "pkgs": [
          {"reference": "elpa-protobuf-mode"},
          {"reference": "libprotobuf-dev"},
          {"reference": "libprotobuf-java"},
          {"reference": "libprotobuf-lite32t64"},
          {"reference": "libprotobuf32t64"},
          {"reference": "libprotoc-dev"},
          {"reference": "libprotoc32t64"},
          {"reference": "php-google-protobuf"},
          {"reference": "protobuf-compiler"},
          {"reference": "python3-protobuf"},
          {"reference": "ruby-google-protobuf"}
        ]
      }
    ]
  },
  "Ubuntu Linux-25.10": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "25.10",
        "pkgs": [
          {"reference": "elpa-protobuf-mode"},
          {"reference": "libprotobuf-dev"},
          {"reference": "libprotobuf-java"},
          {"reference": "libprotobuf-lite32t64"},
          {"reference": "libprotobuf32t64"},
          {"reference": "libprotoc-dev"},
          {"reference": "libprotoc32t64"},
          {"reference": "php-google-protobuf"},
          {"reference": "protobuf-compiler"},
          {"reference": "python3-protobuf"},
          {"reference": "ruby-google-protobuf"}
        ]
      }
    ]
  },
  "Ubuntu Linux-14.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14.04",
        "pkgs": [
          {"reference": "libprotobuf-dev"},
          {"reference": "libprotobuf-java"},
          {"reference": "libprotobuf-lite8"},
          {"reference": "libprotobuf8"},
          {"reference": "libprotoc-dev"},
          {"reference": "libprotoc8"},
          {"reference": "protobuf-compiler"},
          {"reference": "python-protobuf"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "libprotobuf-dev"},
          {"reference": "libprotobuf-java"},
          {"reference": "libprotobuf-lite9v5"},
          {"reference": "libprotobuf9v5"},
          {"reference": "libprotoc-dev"},
          {"reference": "libprotoc9v5"},
          {"reference": "protobuf-compiler"},
          {"reference": "python-protobuf"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "libprotobuf-dev"},
          {"reference": "libprotobuf-java"},
          {"reference": "libprotobuf-lite10"},
          {"reference": "libprotobuf10"},
          {"reference": "libprotoc-dev"},
          {"reference": "libprotoc10"},
          {"reference": "protobuf-compiler"},
          {"reference": "python-protobuf"},
          {"reference": "python3-protobuf"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "libprotobuf-dev"},
          {"reference": "libprotobuf-java"},
          {"reference": "libprotobuf-lite17"},
          {"reference": "libprotobuf17"},
          {"reference": "libprotoc-dev"},
          {"reference": "libprotoc17"},
          {"reference": "protobuf-compiler"},
          {"reference": "python-protobuf"},
          {"reference": "python3-protobuf"},
          {"reference": "ruby-google-protobuf"}
        ]
      }
    ]
  }
};

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 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');
}