CVE-2021-34753

CVE-2021-34753 is a medium-severity vulnerability in Cisco Firepower Threat Defense Software with a CVSS 3.x base score of 5.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-284.

Key facts

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.

Frequently asked questions

What is CVE-2021-34753?
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.
How severe is CVE-2021-34753?
CVE-2021-34753 has a CVSS 3.x base score of 5.8, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2021-34753 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-34753?
CVE-2021-34753 primarily affects Cisco Firepower Threat Defense Software. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-34753?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2021-34753 have an EU (EUVD) identifier?
Yes. CVE-2021-34753 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-21403.
When was CVE-2021-34753 published?
CVE-2021-34753 was published on 2024-11-15 and last updated on 2026-06-17.

References

Affected products (2)

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