CVE Tools
Sign in

CVE-2021-40116

Multiple Cisco Products Snort Rule Denial of Service Vulnerability

Published: Oct 27, 2021Updated: Jul 7, 2025 Sources: CVE List NVD BDUCWE-241
NVD MITRE
8.6CVSSHIGH
EPSS Score
1.3%
Top 32.2%
CISA KEV
Not in KEV
Exploits
0 Known
Remediation
Patch Available

Description

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 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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:CC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-241NVD-CWE-noinfo

Affected Products

Cisco Firepower Threat Defense SoftwareCiscoNetworking Infrastructure
Firepower Threat DefenseCisco Systems Inc.Networking Infrastructure
SnortCisco Systems Inc.Networking Infrastructure
firepower threat defenseciscoNetworking Infrastructure
secure firewall management centerciscoNetworking Infrastructure
ciscocommercialUSNetworking Infrastructureaka cisco systems, cisco systems inc.
cisco systems inc.commercialUSNetworking Infrastructureaka cisco systems, cisco
and 1 more affected products View all →

Exploitability

0 exploit sources identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Official Patch Available

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort-dos-RywH7ezM
tools.cisco.com

Timeline

Published
Oct 27, 2021
Last Updated
Jul 7, 2025

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2021-40116 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
Plain-language analysis
Impact assessment and exploitation scenario in plain English
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows