CVE-2019-1695: Cisco Adaptive Security Appliance and Firepower Threat Defense Software Layer 2 Filtering Bypass Vulnerability

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2019-05-03 · updated 2026-08-11
Weakness: CWE-284

Description

A vulnerability in the detection engine of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, adjacent attacker to send data directly to the kernel of an affected device. The vulnerability exists because the software improperly filters Ethernet frames sent to an affected device. An attacker could exploit this vulnerability by sending crafted packets to the management interface of an affected device. A successful exploit could allow the attacker to bypass the Layer 2 (L2) filters and send data directly to the kernel of the affected device. A malicious frame successfully delivered would make the target device generate a specific syslog entry.

Affected products

Cisco ASA Software: before 9.8.4; from 9.9 before 9.9.2.50; from 9.10 before 9.10.1.17 — fixed in 9.10.1.17, 9.8.4, 9.9.2.50
Cisco Firepower Threat Defense Software: from 6.2.1 before 6.2.3.12; from 6.3.0 before 6.3.0.3 — fixed in 6.2.3.12, 6.3.0.3

How to fix

Upgrade to a fixed version: Cisco ASA Software 9.10.1.17, 9.8.4, 9.9.2.50; Cisco Firepower Threat Defense Software 6.2.3.12, 6.3.0.3. Check the vendor advisory for mitigations.

References

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