CVE-2019-1873: Cisco ASA and FTD Software Cryptographic TLS and SSL Driver Denial of Service Vulnerability

Severity: high (CVSS 8.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2019-07-10 · updated 2026-06-17
Weakness: CWE-400

Description

A vulnerability in the cryptographic driver for Cisco Adaptive Security Appliance Software (ASA) and Firepower Threat Defense (FTD) Software 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. Note: Only traffic directed to the affected system can be used to exploit this vulnerability. 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.

Affected products

Cisco Asa 5506-X Firmware: 9.6(4.16), 9.8(3.8)
Cisco Asa 5506H-X Firmware: 9.6(4.16), 9.8(3.8)
Cisco Asa 5506W-X Firmware: 9.6(4.16), 9.8(3.8)
Cisco Asa 5508-X Firmware: 9.6(4.16), 9.8(3.8)
Cisco Asa 5516-X Firmware: 9.6(4.16), 9.8(3.8)

References

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