Linux Distros Unpatched Vulnerability : CVE-2026-20243

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

include('compat.inc');

if (description)
{
  script_id(324756);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/02");

  script_cve_id("CVE-2026-20243");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-20243");

  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 vulnerability in the ALZ file format parser of ClamAV could allow an unauthenticated, remote attacker to
    cause a DoS condition, or possibly other expanded impacts, resulting from memory corruption on an affected
    device. This vulnerability is due to improper boundary checks for content in ALZ files during scanning,
    which may result in an out-of-bounds buffer write. An attacker could exploit this vulnerability by
    submitting a crafted file that contains ALZ content to be scanned by ClamAV on an affected device. A
    successful exploit could allow the attacker to cause the ClamAV scanning process to terminate, resulting
    in a DoS condition on the affected software. (CVE-2026-20243)

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-2026-20243");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-20243");
  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:"cvss_score_source", value:"CVE-2026-20243");

  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:"2026/07/01");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/02");

  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:canonical:ubuntu_linux:26.04:-:lts");
  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:clamav");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:clamav");
  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", "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-12": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "12",
        "pkgs": [
          {"reference": "clamav"},
          {"reference": "clamav-base"},
          {"reference": "clamav-daemon"},
          {"reference": "clamav-doc"},
          {"reference": "clamav-docs"},
          {"reference": "clamav-freshclam"},
          {"reference": "clamav-milter"},
          {"reference": "clamav-testfiles"},
          {"reference": "clamdscan"},
          {"reference": "libclamav-dev"},
          {"reference": "libclamav12"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "clamav"},
          {"reference": "clamav-base"},
          {"reference": "clamav-daemon"},
          {"reference": "clamav-doc"},
          {"reference": "clamav-docs"},
          {"reference": "clamav-freshclam"},
          {"reference": "clamav-milter"},
          {"reference": "clamav-testfiles"},
          {"reference": "clamdscan"},
          {"reference": "libclamav-dev"},
          {"reference": "libclamav12"}
        ]
      }
    ]
  },
  "Debian Linux-14": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14",
        "pkgs": [
          {"reference": "clamav"},
          {"reference": "clamav-base"},
          {"reference": "clamav-daemon"},
          {"reference": "clamav-doc"},
          {"reference": "clamav-docs"},
          {"reference": "clamav-freshclam"},
          {"reference": "clamav-milter"},
          {"reference": "clamav-testfiles"},
          {"reference": "clamdscan"},
          {"reference": "libclamav-dev"},
          {"reference": "libclamav12"}
        ]
      }
    ]
  },
  "Ubuntu Linux-25.10": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "25.10",
        "pkgs": [
          {"reference": "clamav"},
          {"reference": "clamav-base"},
          {"reference": "clamav-daemon"},
          {"reference": "clamav-doc"},
          {"reference": "clamav-docs"},
          {"reference": "clamav-freshclam"},
          {"reference": "clamav-milter"},
          {"reference": "clamav-testfiles"},
          {"reference": "clamdscan"},
          {"reference": "libclamav-dev"},
          {"reference": "libclamav12"}
        ]
      }
    ]
  },
  "Ubuntu Linux-26.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "26.04",
        "pkgs": [
          {"reference": "clamav"},
          {"reference": "clamav-base"},
          {"reference": "clamav-daemon"},
          {"reference": "clamav-doc"},
          {"reference": "clamav-docs"},
          {"reference": "clamav-freshclam"},
          {"reference": "clamav-milter"},
          {"reference": "clamav-testfiles"},
          {"reference": "clamdscan"},
          {"reference": "libclamav-dev"},
          {"reference": "libclamav12"}
        ]
      }
    ]
  },
  "Debian Linux-11": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "11",
        "pkgs": [
          {"reference": "clamav"},
          {"reference": "clamav-base"},
          {"reference": "clamav-daemon"},
          {"reference": "clamav-docs"},
          {"reference": "clamav-freshclam"},
          {"reference": "clamav-milter"},
          {"reference": "clamav-testfiles"},
          {"reference": "clamdscan"},
          {"reference": "libclamav-dev"},
          {"reference": "libclamav9"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "clamav"},
          {"reference": "clamav-base"},
          {"reference": "clamav-daemon"},
          {"reference": "clamav-docs"},
          {"reference": "clamav-freshclam"},
          {"reference": "clamav-milter"},
          {"reference": "clamav-testfiles"},
          {"reference": "clamdscan"},
          {"reference": "libclamav-dev"},
          {"reference": "libclamav9"}
        ]
      }
    ]
  },
  "Ubuntu Linux-22.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "22.04",
        "pkgs": [
          {"reference": "clamav"},
          {"reference": "clamav-base"},
          {"reference": "clamav-daemon"},
          {"reference": "clamav-docs"},
          {"reference": "clamav-freshclam"},
          {"reference": "clamav-milter"},
          {"reference": "clamav-testfiles"},
          {"reference": "clamdscan"},
          {"reference": "libclamav-dev"},
          {"reference": "libclamav9"}
        ]
      }
    ]
  },
  "Ubuntu Linux-14.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14.04",
        "pkgs": [
          {"reference": "clamav"},
          {"reference": "clamav-base"},
          {"reference": "clamav-daemon"},
          {"reference": "clamav-dbg"},
          {"reference": "clamav-docs"},
          {"reference": "clamav-freshclam"},
          {"reference": "clamav-milter"},
          {"reference": "clamav-testfiles"},
          {"reference": "libclamav-dev"},
          {"reference": "libclamav6"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "clamav"},
          {"reference": "clamav-base"},
          {"reference": "clamav-daemon"},
          {"reference": "clamav-dbg"},
          {"reference": "clamav-docs"},
          {"reference": "clamav-freshclam"},
          {"reference": "clamav-milter"},
          {"reference": "clamav-testfiles"},
          {"reference": "clamdscan"},
          {"reference": "libclamav-dev"},
          {"reference": "libclamav7"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "clamav"},
          {"reference": "clamav-base"},
          {"reference": "clamav-daemon"},
          {"reference": "clamav-docs"},
          {"reference": "clamav-freshclam"},
          {"reference": "clamav-milter"},
          {"reference": "clamav-testfiles"},
          {"reference": "clamdscan"},
          {"reference": "libclamav-dev"},
          {"reference": "libclamav7"}
        ]
      }
    ]
  },
  "Ubuntu Linux-24.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "24.04",
        "pkgs": [
          {"reference": "clamav"},
          {"reference": "clamav-base"},
          {"reference": "clamav-daemon"},
          {"reference": "clamav-docs"},
          {"reference": "clamav-freshclam"},
          {"reference": "clamav-milter"},
          {"reference": "clamav-testfiles"},
          {"reference": "clamdscan"},
          {"reference": "libclamav-dev"},
          {"reference": "libclamav11t64"}
        ]
      }
    ]
  }
};

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');
}