Linux Distros Unpatched Vulnerability : CVE-2026-80213

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

include('compat.inc');

if (description)
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  script_id(342194);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/02");

  script_cve_id("CVE-2026-80213");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-80213");

  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.

  - An issue was discovered in the resolv gem before 0.7.2 for Ruby. Resolv::DNS::MessageEncoder wrote a DNS
    label's length into a single octet without checking its range. A label longer than 255 octets had its
    length stored modulo 256 but the label data was written unchanged, and thus the bytes on the wire
    described a different name than the one the application asked to encode. RFC 1035 section 2.3.4 limits a
    label to 63 octets, and the two high bits of the length octet are reserved for compression pointers.
    put_string packed the length with put_pack(C, d.length) and put_label used it for labels, and thus any
    value from 0 to 255 could end up as a label length octet, including the reserved 0x40-0xBF range and the
    0xC0-0xFF pointer range. Resolv::DNS::Name.create did not check per-label or total name length either, and
    thus an attacker-controlled hostname reached the encoder unchanged. An application that resolves an
    attacker-controlled hostname sends a query whose wire bytes name a domain the attacker chose. A hostname
    suffix that the application validates against an allowlist becomes padding that never appears on the wire,
    and thus allowlist and egress checks can be bypassed. The recursive resolver caches the response under the
    attacker's name, and DNS logs record that name rather than the one the application asked for. A label
    length whose low octet lands in the 0xC0-0xFF range produces a length octet that conforming parsers read
    as the start of a compression pointer, with the following attacker-controlled byte as the offset.
    (CVE-2026-80213)

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-2026-80213");
  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:H/Au:N/C:N/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:H/PR:N/UI:N/S:C/C:N/I:L/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-2026-80213");

  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:"2026/08/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/01");

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  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-8", "Host/OS/Red Hat Enterprise Linux-10", "Host/OS/Red Hat Enterprise Linux-8", "Host/OS/Red Hat Enterprise Linux-9");

  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/RedHat/rpm-list"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Red Hat Enterprise Linux-10": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "10",
        "pkgs": [
          {"reference": "ruby"},
          {"reference": "ruby-bundled-gems"},
          {"reference": "ruby-default-gems"},
          {"reference": "ruby-devel"},
          {"reference": "ruby-doc"},
          {"reference": "ruby-libs"},
          {"reference": "ruby4.0"},
          {"reference": "ruby4.0-devel"},
          {"reference": "ruby4.0-doc"},
          {"reference": "ruby4.0-rubygem-mysql2"},
          {"reference": "ruby4.0-rubygem-pg"},
          {"reference": "rubygem-bigdecimal"},
          {"reference": "rubygem-bundler"},
          {"reference": "rubygem-io-console"},
          {"reference": "rubygem-irb"},
          {"reference": "rubygem-json"},
          {"reference": "rubygem-minitest"},
          {"reference": "rubygem-power_assert"},
          {"reference": "rubygem-psych"},
          {"reference": "rubygem-racc"},
          {"reference": "rubygem-rake"},
          {"reference": "rubygem-rbs"},
          {"reference": "rubygem-rdoc"},
          {"reference": "rubygem-rexml"},
          {"reference": "rubygem-rss"},
          {"reference": "rubygem-test-unit"},
          {"reference": "rubygem-typeprof"},
          {"reference": "rubygems"},
          {"reference": "rubygems-devel"}
        ]
      }
    ]
  },
  "CentOS Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "ruby"},
          {"reference": "ruby-bundled-gems"},
          {"reference": "ruby-default-gems"},
          {"reference": "ruby-devel"},
          {"reference": "ruby-doc"},
          {"reference": "ruby-irb"},
          {"reference": "ruby-libs"},
          {"reference": "rubygem-abrt"},
          {"reference": "rubygem-abrt-doc"},
          {"reference": "rubygem-bigdecimal"},
          {"reference": "rubygem-bson"},
          {"reference": "rubygem-bson-doc"},
          {"reference": "rubygem-bundler"},
          {"reference": "rubygem-bundler-doc"},
          {"reference": "rubygem-did_you_mean"},
          {"reference": "rubygem-io-console"},
          {"reference": "rubygem-irb"},
          {"reference": "rubygem-json"},
          {"reference": "rubygem-minitest"},
          {"reference": "rubygem-mongo"},
          {"reference": "rubygem-mongo-doc"},
          {"reference": "rubygem-mysql2"},
          {"reference": "rubygem-mysql2-doc"},
          {"reference": "rubygem-net-telnet"},
          {"reference": "rubygem-openssl"},
          {"reference": "rubygem-pg"},
          {"reference": "rubygem-pg-doc"},
          {"reference": "rubygem-power_assert"},
          {"reference": "rubygem-psych"},
          {"reference": "rubygem-racc"},
          {"reference": "rubygem-rake"},
          {"reference": "rubygem-rbs"},
          {"reference": "rubygem-rdoc"},
          {"reference": "rubygem-rexml"},
          {"reference": "rubygem-rss"},
          {"reference": "rubygem-test-unit"},
          {"reference": "rubygem-typeprof"},
          {"reference": "rubygem-xmlrpc"},
          {"reference": "rubygems"},
          {"reference": "rubygems-devel"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "ruby"},
          {"reference": "ruby-bundled-gems"},
          {"reference": "ruby-default-gems"},
          {"reference": "ruby-devel"},
          {"reference": "ruby-doc"},
          {"reference": "ruby-irb"},
          {"reference": "ruby-libs"},
          {"reference": "rubygem-abrt"},
          {"reference": "rubygem-abrt-doc"},
          {"reference": "rubygem-bigdecimal"},
          {"reference": "rubygem-bson"},
          {"reference": "rubygem-bson-doc"},
          {"reference": "rubygem-bundler"},
          {"reference": "rubygem-bundler-doc"},
          {"reference": "rubygem-did_you_mean"},
          {"reference": "rubygem-io-console"},
          {"reference": "rubygem-irb"},
          {"reference": "rubygem-json"},
          {"reference": "rubygem-minitest"},
          {"reference": "rubygem-mongo"},
          {"reference": "rubygem-mongo-doc"},
          {"reference": "rubygem-mysql2"},
          {"reference": "rubygem-mysql2-doc"},
          {"reference": "rubygem-net-telnet"},
          {"reference": "rubygem-openssl"},
          {"reference": "rubygem-pg"},
          {"reference": "rubygem-pg-doc"},
          {"reference": "rubygem-power_assert"},
          {"reference": "rubygem-psych"},
          {"reference": "rubygem-racc"},
          {"reference": "rubygem-rake"},
          {"reference": "rubygem-rbs"},
          {"reference": "rubygem-rdoc"},
          {"reference": "rubygem-rexml"},
          {"reference": "rubygem-rss"},
          {"reference": "rubygem-test-unit"},
          {"reference": "rubygem-typeprof"},
          {"reference": "rubygem-xmlrpc"},
          {"reference": "rubygems"},
          {"reference": "rubygems-devel"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-9": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "9",
        "pkgs": [
          {"reference": "ruby"},
          {"reference": "ruby-default-gems"},
          {"reference": "ruby-devel"},
          {"reference": "ruby-doc"},
          {"reference": "ruby-libs"},
          {"reference": "rubygem-bigdecimal"},
          {"reference": "rubygem-bundler"},
          {"reference": "rubygem-io-console"},
          {"reference": "rubygem-irb"},
          {"reference": "rubygem-json"},
          {"reference": "rubygem-minitest"},
          {"reference": "rubygem-power_assert"},
          {"reference": "rubygem-psych"},
          {"reference": "rubygem-rake"},
          {"reference": "rubygem-rbs"},
          {"reference": "rubygem-rdoc"},
          {"reference": "rubygem-rexml"},
          {"reference": "rubygem-rss"},
          {"reference": "rubygem-test-unit"},
          {"reference": "rubygem-typeprof"},
          {"reference": "rubygems"},
          {"reference": "rubygems-devel"}
        ]
      }
    ]
  }
};

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_NOTE,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}