CVE-2020-3317: Cisco Firepower Threat Defense Software SSL Input Validation Denial of Service Vulnerability

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-10-21 · updated 2026-08-11
Weakness: CWE-20

Description

A vulnerability in the ssl_inspection component of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to crash Snort instances. The vulnerability is due to insufficient input validation in the ssl_inspection component. An attacker could exploit this vulnerability by sending a malformed TLS packet through a Cisco Adaptive Security Appliance (ASA). A successful exploit could allow the attacker to crash a Snort instance, resulting in a denial of service (DoS) condition.

Affected products

Cisco Firepower Threat Defense Software: before 6.4.0.10; from 6.5.0 before 6.5.0.5 — fixed in 6.4.0.10, 6.5.0.5

How to fix

Upgrade to a fixed version: Cisco Firepower Threat Defense Software 6.4.0.10, 6.5.0.5. Check the vendor advisory for mitigations.

References

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