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8.6High

Cisco Adaptive Security Appliance Software

CVE-2018-0231

A vulnerability in the Transport Layer Security (TLS) library of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a reload of the affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending a malicious TLS message to an interface enabled for Secure Layer Socket (SSL) services on an affected device. Messages using SSL Version 3 (SSLv3) or SSL Version 2 (SSLv2) cannot be be used to exploit this vulnerability. An exploit could allow the attacker to cause a buffer underflow, triggering a crash on an affected device. This vulnerability affects Cisco ASA Software and Cisco FTD Software that is running on the following Cisco products: Adaptive Security Virtual Appliance (ASAv), Firepower Threat Defense Virtual (FTDv), Firepower 2100 Series Security Appliance. Cisco Bug IDs: CSCve18902, CSCve34335, CSCve38446.

What this means for your business

  • It affects Cisco Adaptive Security Appliance Software. It matters if your company, or a supplier that handles your data, runs it.
  • An attacker can use it remotely, over a network, without a login, and without anyone at your company clicking anything.
  • FIRST's prediction model gives it a 5% chance of attack attempts being seen in the next 30 days, ranking above 91% of all known flaws.

What to do

  1. 1Check whether your company or your suppliers run Cisco Adaptive Security Appliance Software, and which version. The affected versions are listed further down this page.
  2. 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.

Not sure if your company is exposed?

Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.

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Scoring

CVSS
8.6 (v3.0)
Vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Weakness
CWE-20
Assigned by
psirt@cisco.com

Dates

Published
2018-04-19
Last modified
2026-08-11
Sources
NVD

Affected products

  • Cisco Adaptive Security Appliance Software9.8\(1\), 98.1\(1.154\)
  • Cisco Secure Firewall Threat Defense6.0 - 6.1.0.6, 6.2.1 - 6.2.2.1

As listed in the NVD configuration data. Not a statement about your estate.

References