CVE-2023-20177

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

0.7% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2023-11-01 17:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-08-11 19:33 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.7% in the next 30 days (EPSS).
• Severity: 4.0 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2023-11-01 17:15 UTC

Last modified

2026-08-11 19:33 UTC

Exploit probability

0.7% · EPSS, next 30 days

Weakness

CWE-244

Record status

Modified

Affected

• Cisco Secure Firewall Threat Defense 7.0.0
• Cisco Secure Firewall Threat Defense 7.0.0.1
• Cisco Secure Firewall Threat Defense 7.0.1
• Cisco Secure Firewall Threat Defense 7.0.1.1
• Cisco Secure Firewall Threat Defense 7.0.2
• Cisco Secure Firewall Threat Defense 7.0.2.1
• Cisco Secure Firewall Threat Defense 7.0.3
• Cisco Secure Firewall Threat Defense 7.0.4

Attack profile CVSS 3.1 · 4.0

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Changed

Confidentiality

None

Integrity

None

Availability

Low

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2023-20177.md and follow it. Check whether this project is affected by CVE-2023-20177. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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