CVE-2023-20177: A vulnerability in the SSL file policy implementation of Cisco Firepower Threat Defense (FTD) Software that occurs when the SSL/TLS connection is conf...

Description

A vulnerability in the SSL file policy implementation of Cisco Firepower Threat Defense (FTD) Software that occurs when the SSL/TLS connection is configured with a URL Category and the Snort 3 detection engine could allow an unauthenticated, remote attacker to cause the Snort 3 detection engine to unexpectedly restart. This vulnerability exists because a logic error occurs when a Snort 3 detection engine inspects an SSL/TLS connection that has either a URL Category configured on the SSL file policy or a URL Category configured on an access control policy with TLS server identity discovery enabled. Under specific, time-based constraints, an attacker could exploit this vulnerability by sending a crafted SSL/TLS connection through an affected device. A successful exploit could allow the attacker to trigger an unexpected reload of the Snort 3 detection engine, resulting in either a bypass or denial of service (DoS) condition, depending on device configuration. The Snort 3 detection engine will restart automatically. No manual intervention is required.

Metrics

CVSS 3.1

4/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L

EPSS Probability

0.53%

40.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-244

Affected Software

Vendor	Product	Versions
Cisco	Firepower Threat Defense	7.0.0
Cisco	Firepower Threat Defense	7.0.0.1
Cisco	Firepower Threat Defense	7.0.1
Cisco	Firepower Threat Defense	7.0.1.1
Cisco	Firepower Threat Defense	7.0.2
Cisco	Firepower Threat Defense	7.0.2.1
Cisco	Firepower Threat Defense	7.0.3
Cisco	Firepower Threat Defense	7.0.4
Cisco	Firepower Threat Defense	7.0.5
Cisco	Firepower Threat Defense	7.1.0
Cisco	Firepower Threat Defense	7.1.0.1
Cisco	Firepower Threat Defense	7.1.0.2
Cisco	Firepower Threat Defense	7.1.0.3
Cisco	Firepower Threat Defense	7.2.0
Cisco	Firepower Threat Defense	7.2.0.1
Cisco	Firepower Threat Defense	7.2.1
Cisco	Firepower Threat Defense	7.2.2
Cisco	Firepower Threat Defense	7.2.3
Cisco	Firepower Threat Defense	7.3.0
Cisco	Firepower Threat Defense	7.3.1
Cisco	Firepower Threat Defense	7.3.1.1

References

Timeline

Published: Nov 1, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-20177?

A vulnerability in the SSL file policy implementation of Cisco Firepower Threat Defense (FTD) Software that occurs when the SSL/TLS connection is configured with a URL Category and the Snort 3 detection engine could allow an unauthenticated, remote attacker to cause the Snort 3 detection engine to unexpectedly restart. This vulnerability exists because a logic error occurs when a Snort 3 detection engine inspects an SSL/TLS connection that has either a URL Category configured on the SSL file policy or a URL Category configured on an access control policy with TLS server identity discovery enabled. Under specific, time-based constraints, an attacker could exploit this vulnerability by sending a crafted SSL/TLS connection through an affected device. A successful exploit could allow the attacker to trigger an unexpected reload of the Snort 3 detection engine, resulting in either a bypass or denial of service (DoS) condition, depending on device configuration. The Snort 3 detection engine will restart automatically. No manual intervention is required.

How severe is CVE-2023-20177?

CVE-2023-20177 has a CVSS score of 4/10 (MEDIUM severity). The EPSS model estimates a 0.53% probability of exploitation in the next 30 days.

How do I fix CVE-2023-20177?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.