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CVE-2021-34754

Cisco Firepower Threat Defense Software Ethernet Industrial Protocol Policy Bypass Vulnerabilities

5.8 Medium

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
None

Exploit likelihood

1.01%Up 0.5 points since Oct 28, 2021
90%50%10%1%

What each source reports

CVE List Score used 5.8

Cisco Firepower Threat Defense Software Ethernet Industrial Protocol Policy Bypass Vulnerabilities

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.

Record
CVE-2021-34754
CVSS 3.1
5.8 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Weakness
CWE-284
Updated
2026-11-02
EUVDEUVD-2021-21404 5.8

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.

Record
EUVD-2021-21404
CVSS 3.1
5.8 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-3j6c-cpfp-ff5p 7.5

Multiple vulnerabilities in the payload inspection for Ethernet Industrial Protocol (ENIP)...

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.

Record
GHSA-3j6c-cpfp-ff5p
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness
CWE-284
Updated
2026-11-02
NVD 5.8

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.

Record
CVE-2021-34754
CVSS 3.1
5.8 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:P/A:N
Weakness
CWE-284
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
aliases, publishedEUVD
first indexedCVE List, GitHub Advisories, NVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-34754 is a medium vulnerability (CVSS 5.8) in Cisco Firepower Threat Defense Software, published October 27, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.01%, the 63rd percentile. No source names a fixed version.

References

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