Cisco has an update available to mitigate a vulnerability in the cryptographic driver for Adaptive Security Appliance Software (ASA) and Firepower Threat Defense (FTD) Software that could allow an unauthenticated, remote attacker to cause the device to reboot unexpectedly.
The vulnerability is due to incomplete input validation of a Secure Sockets Layer (SSL) or Transport Layer Security (TLS) ingress packet header.
An attacker could exploit this vulnerability by sending a crafted TLS/SSL packet to an interface on the targeted device. An exploit could allow the attacker to cause the device to reload, which will result in a denial of service (DoS) condition, Cisco said in an advisory.
Only traffic directed to the affected system can be used to exploit this vulnerability, Cisco said. This vulnerability affects systems configured in routed and transparent firewall mode and in single or multiple context mode. This vulnerability can be triggered by IPv4 and IPv6 traffic. A valid SSL or TLS session is required to exploit this vulnerability.
Cisco released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco ASA Software or FTD Software:
• ASA 5506-X
• ASA 5506-X with FirePOWER Services
• ASA 5506H-X
• ASA 5506H-X with FirePOWER Services
• ASA 5506W-X
• ASA 5506W-X with FirePOWER Services
• ASA 5508-X
• ASA 5508-X with FirePOWER Services
• ASA 5516-X
• ASA 5516-X with FirePOWER Services
This vulnerability applies only to the ASA hardware platforms that use a specific cryptographic driver for SSL and TLS packet decryption and encryption.
There are multiple features that, when enabled, cause Cisco ASA Software or FTD Software to process SSL/TLS packets.
These features include, but are not limited to, the following:
• AnyConnect and Clientless SSL VPN
• HTTP server used for the management interface