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CVE-2026-20066

Multiple Cisco Products Snort 3 TBD Denial of Service Vulnerability

Published: Mar 4, 2026Updated: Mar 5, 2026 Sources: CVE List NVDCWE-400
NVD MITRE
5.8CVSSMEDIUM
EPSS Score
0.5%
Top 62.8%
CISA KEV
Not in KEV
Exploits
0 Known
Remediation
No Fix Available

Description

Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection. This vulnerability is due to an error in the JSTokenizer normalization logic when the HTTP inspection normalizes JavaScript. An attacker could exploit this vulnerability by sending crafted HTTP packets through an established connection that is parsed by Snort 3. A successful exploit could allow the attacker to cause a DoS condition when the Snort 3 Detection Engine restarts unexpectedly. JSTokenizer is not enabled by default.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:CC:NI:NA:L
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:LAvailability
Low
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Weaknesses

CWE-400

Affected Products

Cisco Secure Firewall Threat Defense (FTD) SoftwareCiscoNetworking Infrastructure
Cisco UTD SNORT IPS Engine SoftwareCiscoNetworking Infrastructure
ciscocommercialUSNetworking Infrastructureaka cisco systems, cisco systems inc.

Attack Graph

Products CVE Techniques Tactics

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Exploitability

0 exploit sources identified

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

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MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-multi-dos-XFWkWSwz
sec.cloudapps.cisco.com

Timeline

Published
Mar 4, 2026
Last Updated
Mar 5, 2026

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