Linux Distros Unpatched Vulnerability : CVE-2026-6638

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

include('compat.inc');

if (description)
{
  script_id(314720);
  script_version("1.6");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/05/26");

  script_cve_id("CVE-2026-6638");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-6638");

  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.

  - SQL injection in PostgreSQL logical replication ALTER SUBSCRIPTION ... REFRESH PUBLICATION allows a
    subscriber table creator to execute arbitrary SQL with the subscription's publication-side credentials.
    The attack takes effect at the next REFRESH PUBLICATION. Within major versions 16, 17, and 18, minor
    versions before PostgreSQL 18.4, 17.10, and 16.14 are affected. Versions before PostgreSQL 16 are
    unaffected. (CVE-2026-6638)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-6638");
  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:C/I:C/A:C");
  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-2026-6638");

  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:"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:"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/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 = {
  "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_HOLE,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}