CVE-2025-20134

Cisco Adaptive Security Appliance and Firepower Threat Defense Software SSL/TLS Certificate Denial of Service Vulnerability

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Published Aug 14, 2025 CVSS 3.1 · 8.6 High EPSS < 1% KEV · Not listed
Description
A vulnerability in the certificate processing of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition.

This vulnerability is due to improper parsing of SSL/TLS certificates. An attacker could exploit this vulnerability by sending crafted DNS packets that match a static Network Address Translation (NAT) rule with DNS inspection enabled through an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2025-24856 A vulnerability in the certificate processing of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to improper parsing of SSL/TLS certificates. An attacker could exploit this vulnerability by sending crafted DNS packets that match a static Network Address Translation (NAT) rule with DNS inspection enabled through an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.
History
Type Values Removed Values Added
Description A vulnerability in the certificate processing of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to improper parsing of&nbsp;SSL/TLS certificates. An attacker could exploit this vulnerability by sending a crafted SSL/TLS certificate to an affected system through a listening SSL/TLS socket. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. A vulnerability in the certificate processing of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to improper parsing of SSL/TLS certificates. An attacker could exploit this vulnerability by sending crafted DNS packets that match a static Network Address Translation (NAT) rule with DNS inspection enabled through an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.
Type Values Removed Values Added
First Time appeared Cisco
Cisco adaptive Security Appliance Software
Cisco firepower Threat Defense Software
Vendors & Products Cisco
Cisco adaptive Security Appliance Software
Cisco firepower Threat Defense Software
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}
Type Values Removed Values Added
Description A vulnerability in the certificate processing of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to improper parsing of&nbsp;SSL/TLS certificates. An attacker could exploit this vulnerability by sending a crafted SSL/TLS certificate to an affected system through a listening SSL/TLS socket. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.
Title Cisco Adaptive Security Appliance and Firepower Threat Defense Software SSL/TLS Certificate Denial of Service Vulnerability
Weaknesses CWE-415
References
Metrics cvssV3_1

{'score': 8.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H'}
Weaknesses

Sources

Status
PUBLISHED
Assigner
cisco
Published
Updated
Aug 19, 2025, 9:41 PM
Reserved
Oct 10, 2024, 7:15 PM

View source JSON

Updated
Aug 14, 2025, 6:42 PM

JSON

Status
Deferred
Published
Aug 14, 2025, 5:15 PM
Modified
Jun 17, 2026, 8:40 AM

View source JSON

No data.

Updated
Aug 15, 2025, 8:07 AM

JSON