Linux Distros Unpatched Vulnerability : CVE-2026-33846

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

include('compat.inc');

if (description)
{
  script_id(311252);
  script_version("1.11");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/06/03");

  script_cve_id("CVE-2026-33846");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-33846");

  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 heap buffer overflow vulnerability exists in the DTLS handshake fragment reassembly logic of GnuTLS. The
    issue arises in merge_handshake_packet() where incoming handshake fragments are matched and merged based
    solely on handshake type, without validating that the message_length field remains consistent across all
    fragments of the same logical message. An attacker can exploit this by sending crafted DTLS fragments with
    conflicting message_length values, causing the implementation to allocate a buffer based on a smaller
    initial fragment and subsequently write beyond its bounds using larger, inconsistent fragments. Because
    the merge operation does not enforce proper bounds checking against the allocated buffer size, this
    results in an out-of-bounds write on the heap. The vulnerability is remotely exploitable without
    authentication via the DTLS handshake path and can lead to application crashes or potential memory
    corruption. (CVE-2026-33846)

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-2026-33846");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-33846");
  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: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: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-2026-33846");

  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:6");
  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-guile");
  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-guile");
  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-6", "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"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-6": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "6",
        "pkgs": [
          {"reference": "gnutls"},
          {"reference": "gnutls-devel"},
          {"reference": "gnutls-guile"},
          {"reference": "gnutls-utils"}
        ]
      }
    ]
  },
  "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');
}