Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software VPN Web Server Denial of Service Vulnerability

SecurityVulns
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A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker to create or delete arbitrary files on the underlying operating system. If critical system files are manipulated, new Remote Access SSL VPN sessions could be denied and existing sessions could be dropped, causing a denial of service (DoS) condition. An exploited device requires a manual reboot to recover.<br><br>
This vulnerability is due to insufficient input validation when processing HTTP requests. An attacker could exploit this vulnerability by sending crafted HTTP requests to an affected device. A successful exploit could allow the attacker to create or delete files on the underlying operating system, which could cause the Remote Access SSL VPN service to become unresponsive.<br><br>
To exploit this vulnerability, the attacker must be authenticated as a VPN user of the affected device.<br><br>

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.<br><br>
This advisory is available at the following link:<br><a href=”https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-http-file-hUyX2jL4″>https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-http-file-hUyX2jL4</a><br><br>

This advisory is part of the August 2025 release of the Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see <a href=”https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-75415″>Cisco Event Response: August 2025 Semiannual Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software Security Advisory Bundled Publication</a>.<br><br>

<br/>Security Impact Rating: High

<br/>CVE: CVE-2025-20251Cisco Security AdvisoryRead More