Linux Distros Unpatched Vulnerability : CVE-2026-6637

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

include('compat.inc');

if (description)
{
  script_id(314721);
  script_version("1.4");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/05/25");

  script_cve_id("CVE-2026-6637");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-6637");

  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.

  - Stack buffer overflow in PostgreSQL module refint allows an unprivileged database user to execute
    arbitrary code as the operating system user running the database. A distinct attack is possible if the
    application declares a user-controlled column as a refint cascade primary key and facilitates user-
    controlled updates to that column. In that case, a SQL injection allows a primary key update value
    provider to execute arbitrary SQL as the database user performing the primary key update. Versions before
    PostgreSQL 18.4, 17.10, 16.14, 15.18, and 14.23 are affected. (CVE-2026-6637)

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-2026-6637");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-6637");
  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:S/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:"cvss_score_source", value:"CVE-2026-6637");

  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:"2026/05/14");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/05/14");

  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:debian:debian_linux:11.0");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:postgresql-10");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:postgresql-12");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:postgresql-9.3");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:postgresql-9.5");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:postgresql-13");
  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/Ubuntu Linux-14.04", "Host/OS/Ubuntu Linux-16.04", "Host/OS/Ubuntu Linux-18.04", "Host/OS/Ubuntu Linux-20.04");

  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-11": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "11",
        "pkgs": [
          {"reference": "libecpg-compat3"},
          {"reference": "libecpg-dev"},
          {"reference": "libecpg6"},
          {"reference": "libpgtypes3"},
          {"reference": "libpq-dev"},
          {"reference": "libpq5"},
          {"reference": "postgresql-13"},
          {"reference": "postgresql-client-13"},
          {"reference": "postgresql-doc-13"},
          {"reference": "postgresql-plperl-13"},
          {"reference": "postgresql-plpython3-13"},
          {"reference": "postgresql-pltcl-13"},
          {"reference": "postgresql-server-dev-13"}
        ]
      }
    ]
  },
  "Ubuntu Linux-14.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14.04",
        "pkgs": [
          {"reference": "libecpg-compat3"},
          {"reference": "libecpg-dev"},
          {"reference": "libecpg6"},
          {"reference": "libpgtypes3"},
          {"reference": "libpq-dev"},
          {"reference": "libpq5"},
          {"reference": "postgresql-9.3"},
          {"reference": "postgresql-9.3-dbg"},
          {"reference": "postgresql-client-9.3"},
          {"reference": "postgresql-contrib-9.3"},
          {"reference": "postgresql-doc-9.3"},
          {"reference": "postgresql-plperl-9.3"},
          {"reference": "postgresql-plpython-9.3"},
          {"reference": "postgresql-plpython3-9.3"},
          {"reference": "postgresql-pltcl-9.3"},
          {"reference": "postgresql-server-dev-9.3"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "libecpg-compat3"},
          {"reference": "libecpg-dev"},
          {"reference": "libecpg6"},
          {"reference": "libpgtypes3"},
          {"reference": "libpq-dev"},
          {"reference": "libpq5"},
          {"reference": "postgresql-9.5"},
          {"reference": "postgresql-9.5-dbg"},
          {"reference": "postgresql-client-9.5"},
          {"reference": "postgresql-contrib-9.5"},
          {"reference": "postgresql-doc-9.5"},
          {"reference": "postgresql-plperl-9.5"},
          {"reference": "postgresql-plpython-9.5"},
          {"reference": "postgresql-plpython3-9.5"},
          {"reference": "postgresql-pltcl-9.5"},
          {"reference": "postgresql-server-dev-9.5"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "libecpg-compat3"},
          {"reference": "libecpg-dev"},
          {"reference": "libecpg6"},
          {"reference": "libpgtypes3"},
          {"reference": "libpq-dev"},
          {"reference": "libpq5"},
          {"reference": "postgresql-10"},
          {"reference": "postgresql-client-10"},
          {"reference": "postgresql-doc-10"},
          {"reference": "postgresql-plperl-10"},
          {"reference": "postgresql-plpython-10"},
          {"reference": "postgresql-plpython3-10"},
          {"reference": "postgresql-pltcl-10"},
          {"reference": "postgresql-server-dev-10"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "libecpg-compat3"},
          {"reference": "libecpg-dev"},
          {"reference": "libecpg6"},
          {"reference": "libpgtypes3"},
          {"reference": "libpq-dev"},
          {"reference": "libpq5"},
          {"reference": "postgresql-12"},
          {"reference": "postgresql-client-12"},
          {"reference": "postgresql-doc-12"},
          {"reference": "postgresql-plperl-12"},
          {"reference": "postgresql-plpython3-12"},
          {"reference": "postgresql-pltcl-12"},
          {"reference": "postgresql-server-dev-12"}
        ]
      }
    ]
  }
};

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');
}