MikroTik RouterOS 7.0.x < 7.23.4 / 7.24.x < 7.24.2 X.509 Signature Validation Bypass (CVE-2026-67278)

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

include('compat.inc');

if (description)
{
  script_id(344587);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/11");

  script_cve_id("CVE-2026-67278");

  script_name(english:"MikroTik RouterOS 7.0.x < 7.23.4 / 7.24.x < 7.24.2 X.509 Signature Validation Bypass (CVE-2026-67278)");

  script_set_attribute(attribute:"synopsis", value:
"The remote networking device is affected by a certificate validation vulnerability.");
  script_set_attribute(attribute:"description", value:
"According to its self-reported version, the remote networking device is running a version of
MikroTik RouterOS 7.0.x prior to 7.23.4, or 7.24.x prior to 7.24.2. It is, therefore, affected by
a certificate validation vulnerability.

MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures during X.509 validation. Because
its trust store includes an e=3 root CA, an attacker controlling or redirecting an outbound
RouterOS TLS connection can use the root's public certificate - without its private key - to forge
a trusted intermediate and issue certificates for arbitrary hostnames, enabling TLS server
impersonation. (CVE-2026-67278)

Note that Nessus has not tested for this issue but has instead relied only on the router's
self-reported version number.");
  script_set_attribute(attribute:"see_also", value:"https://mikrotik.com/supportsec/september-2026-vulnerability/");
  script_set_attribute(attribute:"see_also", value:"https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve");
  # https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?1fe530bb");
  script_set_attribute(attribute:"solution", value:
"Upgrade to MikroTik RouterOS 7.23.4, 7.24.2 or later.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:U");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-67278");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/09/05");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/03");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/10");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:mikrotik:routeros");
  script_set_attribute(attribute:"thorough_tests", value:"true");
  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("mikrotik_detect.nasl", "ssh_detect.nasl");
  script_require_keys("MikroTik/RouterOS/Version");

  exit(0);
}

include('vcf.inc');

var app = 'MikroTik';
var kb_ver = 'MikroTik/RouterOS/Version';

var app_info = vcf::get_app_info(app:app, kb_ver:kb_ver);

var constraints = [
  { 'min_version' : '7.0.0', 'fixed_version' : '7.23.4' },
  { 'min_version' : '7.24', 'fixed_version' : '7.24.2' }
];

vcf::check_version_and_report(app_info:app_info, constraints:constraints, severity:SECURITY_WARNING, strict:FALSE);