CVE-2026-20007
Cisco Secure Firewall Threat Defense Software Snort Deep Inspection Bypass Vulnerability
Description
A vulnerability in the Snort 2 and Snort 3 deep packet inspection of Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured Snort rules and allow traffic onto the network that should have been dropped. This vulnerability is due to a logic error in the integration of the Snort Engine rules with Cisco Secure FTD Software that could allow different Snort rules to be hit when deep inspection of the packet is performed for the inner and outer connections. An attacker could exploit this vulnerability by sending crafted traffic to a targeted device that would hit configured Snort rules. A successful exploit could allow the attacker to send traffic to a network where it should have been denied.
Weakness: CWE-284
Affected products
| Vendor | Product | Category | Matched by |
|---|---|---|---|
| Cisco | Cisco Firepower Threat Defense (FTD) Check your version | Firewall / NGFW | cna-assigner |
Vendor-reported products (1)
- Cisco · Cisco Secure Firewall Threat Defense (FTD) Software
Vendor advisory
cisco-sa-ftd-snort-bypass-rLggKzVF
Cisco Secure Firewall Threat Defense Software Snort Deep Inspection Bypass Vulnerability
Cisco’s rating: Medium (advisory CVSS 5.8) · Published Mar 4, 2026
Bug IDs: CSCwo54753 , CSCwp34291
The vendor’s rating applies to the whole advisory and can differ from this CVE’s own CVSS severity. Where this comes from