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CVE-2025-20133

Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Authentication Targeted Denial of Service Vulnerability

Published: Aug 14, 2025Updated: Aug 15, 2025 Sources: CVE List NVD BDUCWE-401
NVD MITRE
8.6CVSSHIGH
EPSS Score
0.7%
Top 51.7%
CISA KEV
Not in KEV
Exploits
0 Known
Remediation
Patch Available

Description

A vulnerability in the management and VPN web servers of the Remote Access SSL VPN feature of Cisco Secure Firewall ASA Software and Secure FTD Software could allow an unauthenticated, remote attacker to cause the device to unexpectedly stop responding, resulting in a DoS condition. This vulnerability is due to ineffective validation of user-supplied input during the Remote Access SSL VPN authentication process. An attacker could exploit this vulnerability by sending a crafted request to the VPN service on an affected device. A successful exploit could allow the attacker to cause a DoS condition where the device stops responding to Remote Access SSL VPN authentication requests.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:CC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-401

Affected Products

Cisco Adaptive Security Appliance (ASA) SoftwareCisco
On-premSecurity Product
Networking Infrastructure / firewall
Cisco Firepower Threat Defense SoftwareCisco
On-premSecurity Product
Networking Infrastructure / firewall
Firepower Threat DefenseCisco Systems Inc.
On-premSecurity Product
Networking Infrastructure / firewall
Adaptive Security ApplianceCisco Systems Inc.
Network Device
Networking Infrastructure / firewall
ciscocommercialUSNetworking Infrastructureaka cisco systems, cisco systems inc.
cisco systems inc.commercialUSNetworking Infrastructureaka cisco systems, cisco

Exploitability

0 exploit sources identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Official Patch Available

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-vpn-dos-mfPekA6e
sec.cloudapps.cisco.com

Timeline

Published
Aug 14, 2025
Last Updated
Aug 15, 2025

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