CVE-2021-40114: Cisco Secure Firewall Management Center

High severity, CVSS 7.5. EPSS: 2.5% chance of exploitation in the next 30 days.

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.

Affected products

• Cisco Secure Firewall Management Center: version 2.9.14.0 only; version 2.9.15 only; version 2.9.16 only; version 2.9.17 only
• Cisco Secure Firewall Threat Defense: before 6.4.0.12 (fixed in 6.4.0.12); from 6.5.0, before 6.6.3 (fixed in 6.6.3); from 6.7.0, before 6.7.0.2 (fixed in 6.7.0.2)
• Cisco Unified Threat Defense: from 16.12, before 16.12.6 (fixed in 16.12.6); from 17.3, before 17.3.4a (fixed in 17.3.4a); from 17.4, before 17.4.2 (fixed in 17.4.2)
• Snort Snort: from 2.0.0, before 2.9.18 (fixed in 2.9.18)

Published 2021-10-27. Last modified 2026-08-11.