CVE-2021-34754: Cisco Firepower Threat Defense Software Ethernet Industrial Protocol Policy Bypass Vulnerabilities

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: 2021-10-27 · updated 2026-08-11
Weakness: CWE-284

Description

Multiple vulnerabilities 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. These vulnerabilities are due to incomplete processing during deep packet inspection for ENIP packets. An attacker could exploit these vulnerabilities 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 be activated for the ENIP packet.

Affected products

Cisco Firepower Management Center: 2.9.12, 2.9.14.0, 2.9.16, 2.9.17, 2.9.18
Cisco Firepower Threat Defense Software: from 6.4.0 before 6.4.0.13; from 6.6.0 before 6.6.5.1; from 6.7.0 before 6.7.0.3; from 7.0.0 before 7.0.1 — fixed in 6.4.0.13, 6.6.5.1, 6.7.0.3, 7.0.1

How to fix

Upgrade to a fixed version: Cisco Firepower Threat Defense Software 6.4.0.13, 6.6.5.1, 6.7.0.3, 7.0.1. Check the vendor advisory for mitigations.

References

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