Symless Synergy 3.x < 3.9.1 RSA Signature Forgery (node-forge)

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

include('compat.inc');

if (description)
{
  script_id(374139);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/11/02");

  script_cve_id("CVE-2026-85393");

  script_name(english:"Symless Synergy 3.x < 3.9.1 RSA Signature Forgery (node-forge)");

  script_set_attribute(attribute:"synopsis", value:
"An application installed on the remote host is affected by a signature forgery vulnerability.");
  script_set_attribute(attribute:"description", value:
"The version of Symless Synergy installed on the remote host is 3.x prior to 3.9.1. It is, therefore, affected by a
vulnerability in the bundled node-forge library, which Synergy 3 uses to create its own certificate.

  - node-forge through 1.4.0 fails to validate element count in nested DigestAlgorithm sequences during RSA PKCS#1
    v1.5 signature verification. Attackers can embed garbage bytes inside the DigestAlgorithm sequence to forge
    valid signatures for arbitrary messages using low-exponent RSA keys. This is an incomplete fix for
    CVE-2026-33894. (CVE-2026-85393)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  # https://symless.com/synergy/download/release-notes/synergy3-personal/v3.9.1
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?1324d7bf");
  script_set_attribute(attribute:"solution", value:
"Upgrade to Symless Synergy version 3.9.1 or later.");
  script_set_attribute(attribute:"agent", value:"all");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:C/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:N/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:N/PR:N/UI:N/VC:N/VI:H/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-2026-85393");

  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:"2026/09/03");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/10/29");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/30");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:symless:synergy");
  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("symless_synergy_win_detection.nbin", "symless_synergy_nix_detection.nbin", "symless_synergy_macos_installed.nbin");
  script_require_ports("installed_sw/Symless Synergy", "installed_sw/Synergy");

  exit(0);
}

include('vdf.inc');

# The Windows and Linux detections register the install as 'Symless Synergy'; the
# macOS detection registers it as 'Synergy'. Both product names are checked.
# @tvdl-content
var vuln_data = {
  'metadata': {'spec_version': '1.0'},
  'checks': [
    {
      'product': {'name': 'Symless Synergy', 'type': 'app'},
      'check_algorithm': 'default',
      'constraints': [{'min_version': '3.0.0', 'fixed_version': '3.9.1'}]
    },
    {
      'product': {'name': 'Synergy', 'type': 'app'},
      'check_algorithm': 'default',
      'constraints': [{'min_version': '3.0.0', 'fixed_version': '3.9.1'}]
    }
  ]
};

var result = vdf::check_and_report(vuln_data:vuln_data, severity:SECURITY_HOLE);
vdf::handle_check_and_report_errors(vdf_result:result);