CVE-2018-0231: Cisco Adaptive Security Appliance Software

High severity, CVSS 8.6. EPSS: 4.5% chance of exploitation in the next 30 days.

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.

Affected products

• Cisco Adaptive Security Appliance Software: version 9.8(1) only; version 98.1(1.154) only
• Cisco Secure Firewall Threat Defense: from 6.0, before 6.1.0.6 (fixed in 6.1.0.6); from 6.2.1, before 6.2.2.1 (fixed in 6.2.2.1)

Published 2018-04-19. Last modified 2026-08-11.