Linux Distros Unpatched Vulnerability : CVE-2026-63090

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

include('compat.inc');

if (description)
{
  script_id(328294);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/20");

  script_cve_id("CVE-2026-63090");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-63090");

  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.

  - ProFTPD before 1.3.9c and 1.3.10rc3 contains a heap-based buffer overflow vulnerability in the mod_sftp
    module that allows authenticated low-privilege attackers to achieve arbitrary code execution by sending
    crafted SFTP packet fragments exceeding the 16 KB reassembly buffer in the fxp.c component. Attackers can
    supply oversized fragments to trigger an incorrectly conditioned reallocation, corrupt pool freelist
    metadata, overwrite the root_fs BSS global pointer to reference a fake filesystem struct, and redirect
    pr_fsio_stat() to system() via a crafted RENAME request. (CVE-2026-63090)

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-2026-63090");
  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:P/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:L/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:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/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-2026-63090");

  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:"2026/07/20");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/20");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:"p-cpe:/a:debian:debian_linux:proftpd-dfsg");
  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");

  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-11": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "11",
        "pkgs": [
          {"reference": "proftpd-basic"},
          {"reference": "proftpd-core"},
          {"reference": "proftpd-dev"},
          {"reference": "proftpd-doc"},
          {"reference": "proftpd-mod-crypto"},
          {"reference": "proftpd-mod-geoip"},
          {"reference": "proftpd-mod-ldap"},
          {"reference": "proftpd-mod-mysql"},
          {"reference": "proftpd-mod-odbc"},
          {"reference": "proftpd-mod-pgsql"},
          {"reference": "proftpd-mod-snmp"},
          {"reference": "proftpd-mod-sqlite"},
          {"reference": "proftpd-mod-wrap"}
        ]
      }
    ]
  },
  "Debian Linux-12": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "12",
        "pkgs": [
          {"reference": "proftpd-basic"},
          {"reference": "proftpd-core"},
          {"reference": "proftpd-dev"},
          {"reference": "proftpd-doc"},
          {"reference": "proftpd-mod-crypto"},
          {"reference": "proftpd-mod-geoip"},
          {"reference": "proftpd-mod-ldap"},
          {"reference": "proftpd-mod-mysql"},
          {"reference": "proftpd-mod-odbc"},
          {"reference": "proftpd-mod-pgsql"},
          {"reference": "proftpd-mod-snmp"},
          {"reference": "proftpd-mod-sqlite"},
          {"reference": "proftpd-mod-wrap"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "proftpd-core"},
          {"reference": "proftpd-dev"},
          {"reference": "proftpd-doc"},
          {"reference": "proftpd-mod-crypto"},
          {"reference": "proftpd-mod-geoip"},
          {"reference": "proftpd-mod-ldap"},
          {"reference": "proftpd-mod-mysql"},
          {"reference": "proftpd-mod-odbc"},
          {"reference": "proftpd-mod-pgsql"},
          {"reference": "proftpd-mod-snmp"},
          {"reference": "proftpd-mod-sqlite"},
          {"reference": "proftpd-mod-wrap"}
        ]
      }
    ]
  }
};

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');
}