--- id: CVE-2026-20066 title: >- 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 inspect… summary: >- 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 inspect… severity: medium cvss: 5.8 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L' cwe: - CWE-400 vendor: cisco product: snort affected: - 'snort >= 3.0.0-233, < 3.9.7.0' - secure_firewall_threat_defense = 7.4.0 - secure_firewall_threat_defense = 7.4.1 - secure_firewall_threat_defense = 7.4.1.1 - secure_firewall_threat_defense = 7.4.2 - secure_firewall_threat_defense = 7.4.2.1 - secure_firewall_threat_defense = 7.4.2.2 - secure_firewall_threat_defense = 7.4.2.3 - secure_firewall_threat_defense = 7.4.2.4 - secure_firewall_threat_defense = 7.4.3 - secure_firewall_threat_defense = 7.6.0 - secure_firewall_threat_defense = 7.6.1 - secure_firewall_threat_defense = 7.6.2 - secure_firewall_threat_defense = 7.6.2.1 - secure_firewall_threat_defense = 7.7.0 - secure_firewall_threat_defense = 7.7.10 - secure_firewall_threat_defense = 7.7.10.1 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.2.1r - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.2 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.3 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.4 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.4a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.5 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.6 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.7 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.8 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.8a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.4.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.4.1b - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.4.2 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.5.1 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.5.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.2 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.3 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.3a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.4 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.5 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.6 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.6a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.7 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.8 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.8a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.7.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.7.2 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.8.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.2a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.3a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.4 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.4a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.5a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.5e - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.5f - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.6 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.7a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.7b - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.8 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.10.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.11.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.2 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.3 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.3a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.4 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.4a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.4b - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.5 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.5a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.5b - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.5c - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.5d - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.6 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.13.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.14.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.2a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.2c - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.3 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.3a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.4 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.4c - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.16.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.17.1 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.18.1 - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.18.1a - unified_threat_defense_snort_intrusion_prevention_system_engine = 17.18.2 patched: - snort 3.9.7.0 published: '2026-03-04' updated: '2026-08-19' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-20066' references: - url: >- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-multi-dos-XFWkWSwz label: psirt@cisco.com - url: 'https://software.cisco.com' tags: - nvd - csaf - vendor-advisory - cisco epss: 0.00482 epssPercentile: 0.4139 ingestedAt: '2026-08-20T17:59:04.317Z' --- ## Overview 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 - `snort >= 3.0.0-233, < 3.9.7.0` - `secure_firewall_threat_defense = 7.4.0` - `secure_firewall_threat_defense = 7.4.1` - `secure_firewall_threat_defense = 7.4.1.1` - `secure_firewall_threat_defense = 7.4.2` - `secure_firewall_threat_defense = 7.4.2.1` - `secure_firewall_threat_defense = 7.4.2.2` - `secure_firewall_threat_defense = 7.4.2.3` - `secure_firewall_threat_defense = 7.4.2.4` - `secure_firewall_threat_defense = 7.4.3` - `secure_firewall_threat_defense = 7.6.0` - `secure_firewall_threat_defense = 7.6.1` - `secure_firewall_threat_defense = 7.6.2` - `secure_firewall_threat_defense = 7.6.2.1` - `secure_firewall_threat_defense = 7.7.0` - `secure_firewall_threat_defense = 7.7.10` - `secure_firewall_threat_defense = 7.7.10.1` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.2.1r` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.2` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.3` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.4` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.4a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.5` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.6` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.7` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.8` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.3.8a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.4.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.4.1b` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.4.2` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.5.1` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.5.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.2` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.3` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.3a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.4` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.5` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.6` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.6a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.7` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.8` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.6.8a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.7.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.7.2` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.8.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.2a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.3a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.4` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.4a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.5a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.5e` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.5f` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.6` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.7a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.7b` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.9.8` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.10.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.11.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.2` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.3` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.3a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.4` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.4a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.4b` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.5` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.5a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.5b` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.5c` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.5d` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.12.6` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.13.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.14.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.2a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.2c` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.3` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.3a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.4` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.15.4c` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.16.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.17.1` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.18.1` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.18.1a` - `unified_threat_defense_snort_intrusion_prevention_system_engine = 17.18.2` ## Remediation Upgrade past the affected range: - `snort 3.9.7.0` ## Vendor advisories - **cisco-sa-snort3-multi-dos-XFWkWSwz** · Cisco · affected: Cisco UTD SNORT IPS Engine Software (26 versions), Cisco Secure Firewall 4200 Series, Cisco Firepower 2100 Series, Cisco Firepower 1000 Series, Cisco 3000 Series Industrial Security Appliances (ISA), Cisco Firepower 9000 Series, … · updated 2026-03-04 · [advisory](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-multi-dos-XFWkWSwz)