CVE-2026-20066
Multiple Cisco Products Snort 3 TBD Denial of Service Vulnerability
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.
Weakness: CWE-400
Affected products
| Vendor | Product | Category | Matched by |
|---|---|---|---|
| Cisco | Cisco Firepower Threat Defense (FTD) Check your version | Firewall / NGFW | cna-assigner |
| Cisco | Cisco UTD SNORT IPS Engine | Threat Detection & Sandbox | cna-assigner |
Vendor-reported products (2)
- Cisco · Cisco Secure Firewall Threat Defense (FTD) Software
- Cisco · Cisco UTD SNORT IPS Engine Software
Vendor advisory
cisco-sa-snort3-multi-dos-XFWkWSwz
Multiple Cisco Products Snort 3 Denial of Service Vulnerabilities
Cisco’s rating: Medium (advisory CVSS 5.8) · Published Mar 4, 2026
Bug IDs: CSCwn49805 , CSCwn65473 , CSCwo93207 , CSCwo93208 , CSCwp99280 , CSCwq01529 , CSCwq01530 , CSCwq03411 , CSCwq23374 , CSCwq82404 , CSCwq97624 , CSCwq97644 , CSCwq97649 , CSCwr21398
The vendor’s rating applies to the whole advisory and can differ from this CVE’s own CVSS severity. Where this comes from