Secure Firewall Threat Defense
CVE-2026-20007
MEDIUM
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Access control enforcement
MITRE ATT&CK
1 technique across 1 tactic: Defense Evasion The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS 5.8 (MEDIUM). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None. Exploitation no authentication required. Exploitable via remote/network. |
| Exploit ScenarioDerived | A remote attacker without authentication could exploit this vulnerability to send traffic to a network where it should have been denied. |
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Alert meAnalysisAIv1 – Mar 12, 2026
Snort rule bypass in Cisco Secure Firewall Threat Defense allows unauthenticated remote attackers to evade deep packet inspection through crafted traffic that exploits logic errors in inner and outer connection rule evaluation. An attacker can send specially crafted packets that trigger different Snort rules than intended, permitting malicious traffic through the firewall that should be blocked. No patch is currently available for this medium-severity vulnerability.
Earlier versions of this analysis (1)
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. [CVSS 5.8 MEDIUM]
RemediationAI
Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-284 (Improper Access Control). 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
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Primary rating from Vendor (cisco) · only source for this CVE.
CVSS VectorVendor: cisco
DescriptionCVE.org
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.
Executive ViewAI
CVE-2026-20007 presents moderate security risk, a improper access control vulnerability rated CVSS 5.8. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and monitor for exploitation.
Apply vendor patch. If patching is delayed: restrict network access and enable monitoring.
Threat Intelligence Overview
NVD
CVE.org
EPSS
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.
Affected Products (CPE)CVE.org
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Cisco Snort 3 Detection Engine can be remotely restarted by an unauthenticated attacker through crafted HTTP packets exp
Unauthenticated remote attackers can crash the Snort 3 Detection Engine by sending crafted HTTP packets with malformed M
Denial of service in Cisco Snort 3's VBA decompression feature allows unauthenticated remote attackers to crash the dete
Improper error checking in Cisco Snort 3's VBA decompression feature allows unauthenticated remote attackers to trigger
Improper range checking in Cisco Snort 3's VBA decompression feature allows unauthenticated remote attackers to trigger
Denial of service in Cisco Secure Firewall Threat Defense via crafted SSL packets allows unauthenticated remote attacker
Cisco Secure Firewall Threat Defense (FTD) Software is vulnerable to denial of service through improper TLS protocol imp
Snort 3 Detection Engine in multiple Cisco products can be remotely restarted by unauthenticated attackers through craft
A vulnerability in the Internet Key Exchange Version 2 (IKEv2) module of Cisco Secure Firewall Adaptive Security Applian
Snort 3 detection engine contains a vulnerability that allows attackers to cause a DoS condition when the Snort 3 Detect
Snort 3 Detection Engine contains a vulnerability that allows attackers to cause a denial of service (DoS) condition whe
GitHub PoC
Exploit-DB