Cisco ASA Improper Restriction of Operations within the Bounds of a Memory Buffer (CVE-2021-34783)

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

include('compat.inc');

if (description)
{
  script_id(506192);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/07");

  script_cve_id("CVE-2021-34783");

  script_name(english:"Cisco ASA Improper Restriction of Operations within the Bounds of a Memory Buffer (CVE-2021-34783)");

  script_set_attribute(attribute:"synopsis", value:
"The remote OT asset is affected by a vulnerability.");
  script_set_attribute(attribute:"description", value:
"A vulnerability in the software-based SSL/TLS message handler of Cisco
Adaptive Security Appliance (ASA) Software and Firepower Threat
Defense (FTD) Software could allow an unauthenticated, remote attacker
to cause an affected device to reload, resulting in a denial of
service (DoS) condition. This vulnerability is due to insufficient
validation of SSL/TLS messages when the device performs software-based
SSL/TLS decryption. An attacker could exploit this vulnerability by
sending a crafted SSL/TLS message to an affected device. A successful
exploit could allow the attacker to cause the affected device to
reload, resulting in a DoS condition. Note: Datagram TLS (DTLS)
messages cannot be used to exploit this vulnerability.

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-ftd-tls-decrypt-dos-BMxYjm8M
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?3ddc29d7");
  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:N/A:C");
  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:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-34783");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_cwe_id(119, 20);

  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:9.8.0" :
        {"versionEndExcluding" : "9.8.4.40", "versionStartIncluding" : "9.8.0", "family" : "CiscoFirepower"},
    "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:9.14.0" :
        {"versionEndExcluding" : "9.14.3.9", "versionStartIncluding" : "9.14.0", "family" : "CiscoFirepower"},
    "cpe:/o:cisco:adaptive_security_appliance_software:9.15.0" :
        {"versionEndExcluding" : "9.15.1.17", "versionStartIncluding" : "9.15.0", "family" : "CiscoFirepower"},
    "cpe:/o:cisco:adaptive_security_appliance_software:9.16.0" :
        {"versionEndExcluding" : "9.16.2", "versionStartIncluding" : "9.16.0", "family" : "CiscoFirepower"}
};

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