Cyber Resilience

CVE-2021-40116

High

Published: 27 October 2021

Published
27 October 2021
Modified
07 July 2025
KEV Added
Patch
CVSS Score v3.1 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
EPSS Score 0.0078 74.2th percentile
Risk Priority 18 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-40116 is a high-severity Improper Handling of Unexpected Data Type (CWE-241) vulnerability in Cisco Firepower Threat Defense. Its CVSS base score is 8.6 (High).

Operationally, ranked in the top 25.8% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

Multiple Cisco products are affected by a vulnerability in Snort rules 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 handling of the Block with…

more

Reset or Interactive Block with Reset actions if a rule is configured without proper constraints. An attacker could exploit this vulnerability by sending a crafted IP packet to the affected device. A successful exploit could allow the attacker to cause through traffic to be dropped. Note: Only products with Snort3 configured and either a rule with Block with Reset or Interactive Block with Reset actions configured are vulnerable. Products configured with Snort2 are not vulnerable.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

cisco
firepower threat defense
6.4.0 — 6.4.0.13 · 6.6.0 — 6.6.5.1 · 6.7.0 — 6.7.0.3
cisco
secure firewall management center
3.1.0.1
cisco
snort
3.0.0.0 — 3.1.0.100

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References