Linux Distros Unpatched Vulnerability : CVE-2026-42013

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

include('compat.inc');

if (description)
{
  script_id(311229);
  script_version("1.11");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/06/03");

  script_cve_id("CVE-2026-42013");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-42013");

  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 flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name (SAN)
    could cause the validation process to incorrectly fall back to checking the Common Name (CN) field. This
    could allow a remote attacker to bypass proper certificate validation, potentially leading to spoofing or
    man-in-the-middle attacks. (CVE-2026-42013)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/cve/cve-2026-42013");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-42013");
  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:M/Au:N/C:P/I:P/A:N");
  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:L/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-42013");

  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:"plugin_publication_date", value:"2026/04/30");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:centos:centos:7");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:7");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:gnutls28");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:gnutls");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:gnutls-c++");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:gnutls-dane");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:gnutls-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:gnutls-utils");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:gnutls");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:gnutls-c++");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:gnutls-dane");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:gnutls-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:gnutls-utils");
  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/CentOS Linux-7", "Host/OS/Red Hat Enterprise Linux-7", "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/CentOS/rpm-list")) && empty_or_null(get_one_kb_item("Host/Debian/dpkg-l")) && empty_or_null(get_one_kb_item("Host/RedHat/rpm-list"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "gnutls-bin"},
          {"reference": "gnutls-doc"},
          {"reference": "guile-gnutls"},
          {"reference": "libgnutls-dev"},
          {"reference": "libgnutls-openssl27"},
          {"reference": "libgnutls28-dev"},
          {"reference": "libgnutls30"},
          {"reference": "libgnutlsxx28"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "gnutls-bin"},
          {"reference": "gnutls-doc"},
          {"reference": "libgnutls-dane0"},
          {"reference": "libgnutls-openssl27"},
          {"reference": "libgnutls28-dev"},
          {"reference": "libgnutls30"},
          {"reference": "libgnutlsxx28"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "gnutls-bin"},
          {"reference": "gnutls-doc"},
          {"reference": "guile-gnutls"},
          {"reference": "libgnutls-dane0"},
          {"reference": "libgnutls-openssl27"},
          {"reference": "libgnutls28-dev"},
          {"reference": "libgnutls30"},
          {"reference": "libgnutlsxx28"}
        ]
      }
    ]
  },
  "CentOS Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "gnutls"},
          {"reference": "gnutls-c++"},
          {"reference": "gnutls-dane"},
          {"reference": "gnutls-devel"},
          {"reference": "gnutls-utils"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "gnutls"},
          {"reference": "gnutls-c++"},
          {"reference": "gnutls-dane"},
          {"reference": "gnutls-devel"},
          {"reference": "gnutls-utils"}
        ]
      }
    ]
  }
};

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');
}