Summary

• Update: On November 5, 2025, Cisco became aware of a new attack variant against devices running Cisco Secure ASA Software or Cisco Secure FTD Software releases that are affected by CVE-2025-20333 and CVE-2025-20362. This attack can cause unpatched devices to unexpectedly reload, leading to denial of service (DoS) conditions. Cisco strongly recommends that all customers upgrade to the fixed software releases that are listed in the Fixed Software section of this advisory.

  A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker to execute arbitrary code on an affected device.

  This vulnerability is due to improper validation of user-supplied input in HTTP(S) requests. An attacker with valid VPN user credentials could exploit this vulnerability by sending crafted HTTP requests to an affected device. A successful exploit could allow the attacker to execute arbitrary code as root, possibly resulting in the complete compromise of the affected device.

  Cisco has released software updates that address this vulnerability. Cisco continues to strongly recommend that customers upgrade to a fixed software release to remediate this vulnerability. There are no workarounds that address this vulnerability.

  This advisory is available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-webvpn-z5xP8EUB

  For more information on the vulnerability that is described in this advisory, see Cisco Event Response: Continued Attacks Against Cisco Firewall Platforms.

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco devices if they are running a vulnerable release of Cisco Secure Firewall ASA Software or Cisco Secure FTD Software and have one or more of the vulnerable configurations listed in the following two tables.

  For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.

  Cisco Secure Firewall ASA Software Vulnerable Configurations

  In the following table, the left column lists Cisco Secure Firewall ASA Software features that are potentially vulnerable. The right column indicates the basic configuration for the feature from the show running-config CLI command, if it can be determined. These features could cause the SSL listen sockets to be enabled.

  Cisco Secure Firewall ASA Software Feature	Possible Vulnerable Configuration
  AnyConnect IKEv2 Remote Access (with client services)	crypto ikev2 enable <interface name> client-services port <port_numbers>
  Mobile User Security (MUS)	webvpn mus password mus server enable <port_number> mus <IPv4_address> <IPv4_mask> <interface_name>
  SSL VPN	webvpn enable <interface_name>

  Cisco Secure Firewall FTD Software Vulnerable Configurations

  In the following table, the left column lists Cisco Secure Firewall FTD Software features that are potentially vulnerable. The right column indicates the basic configuration for the feature from the show running-config CLI command, if it can be determined. These features could cause the SSL listen sockets to be enabled.

  Cisco Secure FTD Software Feature	Possible Vulnerable Configuration
  AnyConnect IKEv2 Remote Access (with client services)	crypto ikev2 enable <interface_name> client-services port <port_number>
  AnyConnect SSL VPN	webvpn enable <interface_name>

  Remote access VPN features are enabled from Devices > VPN > Remote Access in Cisco Secure Firewall Management Center (FMC) Software or from Device > Remote Access VPN in Cisco Secure Firewall Device Manager (FDM).

  Products Confirmed Not Vulnerable

  Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.

  Cisco has confirmed that this vulnerability does not affect Cisco Secure FMC Software.

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

• Cisco considers any workarounds and mitigations to be temporary solutions until an upgrade to a fixed software release is available. To fully remediate this vulnerability and avoid future exposure as described in this advisory, Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.

  Cisco Secure Firewall ASA Software Releases 9.12 and 9.14

  For the following Cisco ASA 5500-X Series models that are running Cisco Secure Firewall ASA Software Release 9.12 or 9.14, use the hidden Cisco Secure Firewall ASA Software Release 9.12.4.72 or 9.14.4.28. For all other platforms, use the Cisco Software Checker to determine the first fixed release.

  • 5512-X and 5515-X - Last Date of Support: August 31, 2022
  • 5525-X, 5545-X, and 5555-X - Last Date of Support: September 30, 2025
  • 5585-X - Last Date of Support: May 31, 2023

  Cisco Secure Firewall ASA Software Release 9.12.4.72 is available from the Cisco Software Download Center.
  Cisco Secure Firewall ASA Software Release 9.14.4.28 is available from the Cisco Software Download Center.

  These are the final releases for Cisco Secure Firewall ASA Software releases 9.12 and 9.14.

  Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software

  To help customers determine their exposure to vulnerabilities in Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software, Cisco provides the Cisco Software Checker. This tool identifies any Cisco security advisories that impact a specific software release and the earliest release that fixes the vulnerabilities that are described in each advisory (“First Fixed”). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities that are described in all the advisories that the Software Checker identifies (“Combined First Fixed”).

  To use the tool, go to the Cisco Software Checker page and follow the instructions. Alternatively, use the following form to search for vulnerabilities that affect a specific software release. To use the form, follow these steps:

  1. Choose which advisories the tool will search-all advisories, only advisories with a Critical or High Security Impact Rating (SIR), or only this advisory.
  2. Choose the appropriate software.
  3. Choose the appropriate platform.
  4. Enter a release number-for example, 9.20.3.4 for Cisco Secure Firewall ASA Software or 7.4.2 for Cisco Secure FTD Software.
  5. Click Check.

  Only this advisory All Critical and High advisories All advisories Cisco ASA Software Cisco FMC Software Cisco FTD Software Any Platform 3000 Series Industrial Security Appliances (ISA) ASA 5500-X Series Firewalls ASA Service Module Adaptive Security Virtual Appliance (ASAv) Firepower 1000 Series Firepower 2100 Series Firepower 4100 Series Firepower 9000 Series Secure Firewall 1200 Series Secure Firewall 3100 Series Secure Firewall 4200 Series

Recommendations

• After installing a fixed release, it is recommended that customers review the Configure Threat Detection for VPN Services section of the Cisco Secure Firewall ASA Firewall CLI Configuration Guide. This section will provide guidance on enabling protections from remote access VPN login authentication attacks, client initiation attacks, and attempts to connect to an invalid VPN service. Determining which protections are needed is at the discretion of the customer.

Exploitation and Public Announcements

• The Cisco Product Security Incident Response Team (PSIRT) is aware of attempted exploitation of this vulnerability. Cisco continues to strongly recommend that customers upgrade to a fixed software release to remediate this vulnerability.

Source

• This vulnerability was found during the resolution of a Cisco Technical Assistance Center (TAC) support case.

  Cisco would like to thank the following organizations for supporting this investigation:

  • The Australian Signals Directorate Australian Cyber Security Centre
  • The Canadian Centre for Cyber Security, a part of the Communications Security Establishment
  • The UK National Cyber Security Centre (NCSC)
  • The U.S. Cybersecurity & Infrastructure Security Agency (CISA)

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-webvpn-z5xP8EUB

Revision History

• Version	Description	Section	Status	Date
  2.1	Fixed the Cisco Software Checker template. Added information on first fixed releases for Cisco Secure Firewall ASA Software releases 9.12 and 9.14.	Fixed Software	Final	2025-NOV-06
  2.0	Added information about a new attack variant.	Summary	Final	2025-NOV-05
  1.0	Initial public release.	-	Final	2025-SEP-25

  Show Less