CVE-2026-20290
Cisco Secure Firewall Threat Defense Software Snort 2 SSL/TLS Denial of Service Vulnerability
Published Sep 16, 2026
CVSS 3.1 · 5.8 Medium
EPSS < 1%
KEV · Not listed
Description
A vulnerability in SSL/TLS certificate parsing in the Snort 2 Detection Engine of Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the Snort 2 Detection Engine to restart.
This vulnerability is due to incomplete validation of the SSL certificate. An attacker could exploit this vulnerability by sending a crafted SSL connection setup request to be parsed by Snort 2. A successful exploit could allow the attacker to cause the Snort 2 Detection Engine to restart unexpectedly, resulting in a denial of service (DoS) condition.
This vulnerability is due to incomplete validation of the SSL certificate. An attacker could exploit this vulnerability by sending a crafted SSL connection setup request to be parsed by Snort 2. A successful exploit could allow the attacker to cause the Snort 2 Detection Engine to restart unexpectedly, resulting in a denial of service (DoS) condition.
Affected Products
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CVE record
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NVD configurations
No data
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Red Hat packages
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OpenCVE enrichment
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Cisco | Cisco Secure Firewall Threat Defense (FTD) Software | unknown |
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No data.
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| Cisco | Secure Firewall Threat Defense |
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Remediation
Tracking
Advisories
Metrics
No CVSS v4.0
Attack Vector Network
Attack Complexity Low
Privileges Required None
Scope Changed
Confidentiality Impact None
Integrity Impact None
Availability Impact Low
User Interaction None
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.309% probability within 30 days)
Exploitation none
Automatable yes
Technical Impact partial
References
History
Sep 18, 2026 9:30 PM
First appearance in the feed. Affected vendors updated
View changes
| Type | Values Removed | Values Added |
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| First Time appeared |
Cisco
Cisco secure Firewall Threat Defense |
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| Vendors & Products |
Cisco
Cisco secure Firewall Threat Defense |
Sep 17, 2026 6:30 PM
Scoring metrics updated
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| Type | Values Removed | Values Added |
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| Metrics |
ssvc
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Sep 16, 2026 8:30 PM
Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | A vulnerability in SSL/TLS certificate parsing in the Snort 2 Detection Engine of Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the Snort 2 Detection Engine to restart. This vulnerability is due to incomplete validation of the SSL certificate. An attacker could exploit this vulnerability by sending a crafted SSL connection setup request to be parsed by Snort 2. A successful exploit could allow the attacker to cause the Snort 2 Detection Engine to restart unexpectedly, resulting in a denial of service (DoS) condition. | |
| Title | Cisco Secure Firewall Threat Defense Software Snort 2 SSL/TLS Denial of Service Vulnerability | |
| Weaknesses | CWE-805 | |
| References |
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| Metrics |
cvssV3_1
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Subscriptions
Weaknesses
