Cisco ASA Improper Input Validation (CVE-2021-34790)

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

include('compat.inc');

if (description)
{
  script_id(506140);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/07");

  script_cve_id("CVE-2021-34790");

  script_name(english:"Cisco ASA Improper Input Validation (CVE-2021-34790)");

  script_set_attribute(attribute:"synopsis", value:
"The remote OT asset is affected by a vulnerability.");
  script_set_attribute(attribute:"description", value:
"Multiple vulnerabilities in the Application Level Gateway (ALG) for
the Network Address Translation (NAT) feature of Cisco Adaptive
Security Appliance (ASA) Software and Firepower Threat Defense (FTD)
Software could allow an unauthenticated, remote attacker to bypass the
ALG and open unauthorized connections with a host located behind the
ALG. For more information about these vulnerabilities, see the Details
section of this advisory. Note: These vulnerabilities have been
publicly discussed as NAT Slipstreaming.

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.");
  # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-natalg-bypass-cpKGqkng
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?8ee1c5de");
  script_set_attribute(attribute:"solution", value:
"Refer to the vendor advisory.");
  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:N/I:L/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-34790");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_cwe_id(20, 358);

  script_set_attribute(attribute:"vuln_publication_date", value:"2021/10/27");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/10/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/06");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:adaptive_security_appliance_software:9");
  script_set_attribute(attribute:"generated_plugin", value:"former");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Tenable.ot");

  script_copyright(english:"This script is Copyright (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("tenable_ot_api_integration.nasl");
  script_require_keys("Tenable.ot/Cisco");

  exit(0);
}


include('tenable_ot_cve_funcs.inc');

get_kb_item_or_exit('Tenable.ot/Cisco');

var asset = tenable_ot::assets::get(vendor:'Cisco');

var vuln_cpes = {
    "cpe:/o:cisco:adaptive_security_appliance_software:9.12.0" :
        {"versionEndExcluding" : "9.12.4.29", "versionStartIncluding" : "9.12.0", "family" : "CiscoFirepower"},
    "cpe:/o:cisco:adaptive_security_appliance_software:9.13.0" :
        {"versionEndExcluding" : "9.14.2.15", "versionStartIncluding" : "9.13.0", "family" : "CiscoFirepower"},
    "cpe:/o:cisco:adaptive_security_appliance_software:9.15.0" :
        {"versionEndExcluding" : "9.15.1.15", "versionStartIncluding" : "9.15.0", "family" : "CiscoFirepower"}
};

tenable_ot::cve::compare_and_report(asset:asset, cpes:vuln_cpes, severity:SECURITY_WARNING);