Rapid7

vulnerability

Cisco FTD: CVE-2021-34753: Cisco Firepower Threat Defense Software Ethernet Industrial Protocol Policy Bypass Vulnerabilities

Severity
5
CVSS
(AV:N/AC:L/Au:N/C:N/I:P/A:N)
Published
Oct 27, 2021
Added
Jan 29, 2025
Modified
Mar 31, 2026

Description

A vulnerability in the payload inspection for Ethernet Industrial Protocol (ENIP) traffic for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured rules for ENIP traffic.

This vulnerability is due to incomplete processing during deep packet inspection for ENIP packets. An attacker could exploit this vulnerability by sending a crafted ENIP packet to the targeted interface. A successful exploit could allow the attacker to bypass configured access control and intrusion policies that should trigger and drop for the ENIP packet.

Solution

cisco-ftd-upgrade-latest
Title
Rapid7 Labs

2026 Global Threat Landscape Report

The predictive window has collapsed. Exploitation follows disclosure in days. See how attackers are accelerating and how to stay ahead.