CVE-2021-40114: Multiple Cisco products are affected by a vulnerability in the way the Snort detection engine processes ICMP traffic that could allow an unauthenticat...

Description

Multiple Cisco products are affected by a vulnerability in the way the Snort detection engine processes ICMP traffic that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper memory resource management while the Snort detection engine is processing ICMP packets. An attacker could exploit this vulnerability by sending a series of ICMP packets through an affected device. A successful exploit could allow the attacker to exhaust resources on the affected device, causing the device to reload.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

2.37%

81.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Cisco	Firepower Threat Defense	< 6.4.0.12
Cisco	Firepower Threat Defense	>= 6.5.0, < 6.6.3
Cisco	Firepower Threat Defense	>= 6.7.0, < 6.7.0.2
Cisco	Secure Firewall Management Center	2.9.14.0
Cisco	Secure Firewall Management Center	2.9.15
Cisco	Secure Firewall Management Center	2.9.16
Cisco	Secure Firewall Management Center	2.9.17
Cisco	Unified Threat Defense	>= 16.12, < 16.12.6
Cisco	Unified Threat Defense	>= 17.3, < 17.3.4a
Cisco	Unified Threat Defense	>= 17.4, < 17.4.2
Snort	Snort	>= 2.0.0, < 2.9.18

References

Timeline

Published: Oct 27, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-40114?

Multiple Cisco products are affected by a vulnerability in the way the Snort detection engine processes ICMP traffic that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper memory resource management while the Snort detection engine is processing ICMP packets. An attacker could exploit this vulnerability by sending a series of ICMP packets through an affected device. A successful exploit could allow the attacker to exhaust resources on the affected device, causing the device to reload.

How severe is CVE-2021-40114?

CVE-2021-40114 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 2.37% probability of exploitation in the next 30 days.

How do I fix CVE-2021-40114?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.