CVE-2026-20066

EUVD-2026-9465

04.03.2026, 18:16

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.

Provider	Type	Base Score	Atk. Vector	Atk. Complexity	Priv. Required	Vector
NIST	Primary	5.8 MEDIUM	NETWORK	LOW	NONE	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

Base Score

CVSS 3.x

EPSS Score

Percentile: 37.77%

Affected Products (NVD)

Vendor	Product	Version
cisco	snort	3.0.0-233 ≤ 𝑥 < 3.9.7.0
cisco	secure_firewall_threat_defense	7.4.0
cisco	secure_firewall_threat_defense	7.4.1
cisco	secure_firewall_threat_defense	7.4.1.1
cisco	secure_firewall_threat_defense	7.4.2
cisco	secure_firewall_threat_defense	7.4.2.1
cisco	secure_firewall_threat_defense	7.4.2.2
cisco	secure_firewall_threat_defense	7.4.2.3
cisco	secure_firewall_threat_defense	7.4.2.4
cisco	secure_firewall_threat_defense	7.4.3
cisco	secure_firewall_threat_defense	7.6.0
cisco	secure_firewall_threat_defense	7.6.1
cisco	secure_firewall_threat_defense	7.6.2
cisco	secure_firewall_threat_defense	7.6.2.1
cisco	secure_firewall_threat_defense	7.7.0
cisco	secure_firewall_threat_defense	7.7.10
cisco	secure_firewall_threat_defense	7.7.10.1
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.2.1r:r
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.3.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.3.2
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.3.3
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.3.4
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.3.4a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.3.5
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.3.6
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.3.7
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.3.8
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.3.8a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.4.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.4.1b:b
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.4.2
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.5.1
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.5.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.6.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.6.2
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.6.3
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.6.3a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.6.4
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.6.5
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.6.6
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.6.6a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.6.7
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.6.8
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.6.8a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.7.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.7.2
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.8.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.9.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.9.2a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.9.3a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.9.4
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.9.4a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.9.5a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.9.5e:e
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.9.5f:f
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.9.6
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.9.7a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.9.7b:b
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.9.8
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.10.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.11.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.12.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.12.2
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.12.3
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.12.3a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.12.4
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.12.4a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.12.4b:b
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.12.5
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.12.5a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.12.5b:b
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.12.5c:c
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.12.5d:d
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.12.6
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.13.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.14.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.15.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.15.2a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.15.2c:c
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.15.3
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.15.3a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.15.4
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.15.4c:c
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.16.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.17.1
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.18.1
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.18.1a:a
cisco	unified_threat_defense_snort_intrusion_prevention_system_engine	17.18.2

𝑥

= Vulnerable software versions

Common Weakness Enumeration

CWE-400 - Uncontrolled Resource Consumption
The software 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

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