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CVE

CVE-2021-40116

Multiple Cisco products are affected by a vulnerability in Snort rules that could allow an unauthenticated, remote attac

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.

HIGH · CVSS 8.6 EPSS 0.00784
Schedule remediation
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
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Weakness Classification

CWE-241Improper Handling of Unexpected Data Type
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Affected Products & Versions

6
cisco firepower threat defense>= 6.4.0 and < 6.4.0.13
cisco firepower threat defense>= 6.6.0 and < 6.6.5.1
cisco firepower threat defense>= 6.7.0 and < 6.7.0.3
cisco firepower threat defense>= 7.0.0 and < 7.0.1
cisco secure firewall management centerall versions
cisco snort>= 3.0.0.0 and < 3.1.0.100
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Scoring & Timeline

8.6
HIGH · CVSS v3.1 · psirt@cisco.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD27 Oct 2021 · 07:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

1
cisco-csafcisco-sa-snort-dos-RywH7ezM
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort-dos-RywH7ezMVendor Advisory
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