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CVE-2023-20177

A vulnerability in the SSL file policy implementation of Cisco Firepower Threat Defense (FTD)...

4.0 Medium

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
Low

Exploit likelihood

0.71%Up 0.7 points since Nov 2, 2023
90%50%10%1%

What each source reports

CVE List Score used 4.0

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.

Record
CVE-2023-20177
CVSS 3.1
4.0 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L
Weakness
CWE-244
Updated
2026-11-02
EUVDEUVD-2023-24356 4.0

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.

Record
EUVD-2023-24356
CVSS 3.1
4.0 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L
Updated
2026-11-03
GitHub AdvisoriesGHSA-753m-gv8q-x327 4.0

A vulnerability in the SSL file policy implementation of Cisco Firepower Threat Defense (FTD)...

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.

Record
GHSA-753m-gv8q-x327
CVSS 3.1
4.0 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L
Weakness
CWE-244
Updated
2026-11-02
NVD 4.0

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.

Record
CVE-2023-20177
CVSS 3.1
4.0 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L
Weakness
CWE-244
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
aliases, publishedEUVD
first indexedCVE List, GitHub Advisories, NVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2023-20177 is a medium vulnerability (CVSS 4.0) in Cisco Firepower Threat Defense Software, published November 1, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.71%, the 53rd percentile. No source names a fixed version.

References

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