CVE-2026-20066

Published: Mar 4, 2026Modified: Aug 19, 2026

5.8

Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

Exploitability: 3.9 / Impact: 1.4

Source: psirt@cisco.com (Secondary)

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.

Affected (88)

Products: Cisco: Snort, Secure Firewall Threat Defense, Unified Threat Defense Snort Intrusion Prevention System Engine

Cisco

3 products

Snort

Secure Firewall Threat Defense

Unified Threat Defense Snort Intrusion Prevention System Engine

Configuration A

1 vulnerable

Vulnerable Software	Affected Versions
Cisco Snort	From 3.0.0-233 to 3.9.7.0

Configuration B

16 vulnerable

Vulnerable Software	Affected Versions
Cisco Secure Firewall Threat Defense	Version 7.4.0
Cisco Secure Firewall Threat Defense	Version 7.4.1.1
Cisco Secure Firewall Threat Defense	Version 7.4.1
Cisco Secure Firewall Threat Defense	Version 7.4.2.1
Cisco Secure Firewall Threat Defense	Version 7.4.2.2
Cisco Secure Firewall Threat Defense	Version 7.4.2.3
Cisco Secure Firewall Threat Defense	Version 7.4.2.4
Cisco Secure Firewall Threat Defense	Version 7.4.2
Cisco Secure Firewall Threat Defense	Version 7.4.3
Cisco Secure Firewall Threat Defense	Version 7.6.0
Cisco Secure Firewall Threat Defense	Version 7.6.1
Cisco Secure Firewall Threat Defense	Version 7.6.2.1
Cisco Secure Firewall Threat Defense	Version 7.6.2
Cisco Secure Firewall Threat Defense	Version 7.7.0
Cisco Secure Firewall Threat Defense	Version 7.7.10.1
Cisco Secure Firewall Threat Defense	Version 7.7.10

Configuration C

71 vulnerable

Vulnerable Software	Affected Versions
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.10.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.11.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.12.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.12.2
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.12.3
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.12.3a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.12.4
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.12.4a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.12.4b
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.12.5
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.12.5a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.12.5b
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.12.5c
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.12.5d
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.12.6
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.13.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.14.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.15.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.15.2a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.15.2c
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.15.3
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.15.3a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.15.4
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.15.4c
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.16.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.17.1
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.18.1
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.18.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.18.2
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.2.1r
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.3.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.3.2
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.3.3
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.3.4
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.3.4a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.3.5
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.3.6
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.3.7
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.3.8
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.3.8a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.4.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.4.1b
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.4.2
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.5.1
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.5.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.6.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.6.2
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.6.3
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.6.3a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.6.4
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.6.5
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.6.6
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.6.6a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.6.7
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.6.8
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.6.8a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.7.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.7.2
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.8.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.9.1a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.9.2a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.9.3a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.9.4
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.9.4a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.9.5a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.9.5e
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.9.5f
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.9.6
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.9.7a
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.9.7b
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine	Version 17.9.8

Related CWEs

CWE-400

Uncontrolled Resource Consumption

The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.

References (1)

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

Source: psirt@cisco.com

Vendor Advisory

Timeline

No history available yet.