CVE-2018-0296: Cisco Adaptive Security Appliance (ASA) Denial-of-Service Vulnerability

High severity, CVSS 7.5. Actively exploited: in CISA KEV since 2021-11-03. EPSS: 99.9% chance of exploitation in the next 30 days.

A vulnerability in the web interface of the Cisco Adaptive Security Appliance (ASA) could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. It is also possible on certain software releases that the ASA will not reload, but an attacker could view sensitive system information without authentication by using directory traversal techniques. The vulnerability is due to lack of proper input validation of the HTTP URL. An attacker could exploit this vulnerability by sending a crafted HTTP request to an affected device. An exploit could allow the attacker to cause a DoS condition or unauthenticated disclosure of information. This vulnerability applies to IPv4 and IPv6 HTTP traffic. This vulnerability affects Cisco ASA Software and Cisco Firepower Threat Defense (FTD) Software that is running on the following Cisco products: 3000 Series Industrial Security Appliance (ISA), ASA 1000V Cloud Firewall, ASA 5500 Series Adaptive Security Appliances, ASA 5500-X Series Next-Generation Firewalls, ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers, Adaptive Security Virtual Appliance (ASAv), Firepower 2100 Series Security Appliance, Firepower 4100 Series Security Appliance, Firepower 9300 ASA Security Module, FTD Virtual (FTDv). Cisco Bug IDs: CSCvi16029.

Affected products

  • Cisco Adaptive Security Appliance Software: from 9.1, before 9.1.7.29 (fixed in 9.1.7.29); from 9.2, before 9.2.4.33 (fixed in 9.2.4.33); from 9.3, before 9.4.4.18 (fixed in 9.4.4.18); from 9.5, before 9.6.4.8 (fixed in 9.6.4.8); from 9.7, before 9.7.1.24 (fixed in 9.7.1.24); from 9.8, before 9.8.2.28 (fixed in 9.8.2.28); …
  • Cisco Firepower Threat Defense: version 6.2.3-85.02 only; version 6.2.3-851 only
  • Cisco Secure Firewall Threat Defense: from 6.0, before 6.1.0 (fixed in 6.1.0); from 6.2.1, before 6.2.2.3 (fixed in 6.2.2.3); version 6.2.3 only; version 6.2.3.1 only

Published 2018-06-07. Last modified 2026-08-11.