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Vulnerabilities

Vulnerability · CVE-2025-20133

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 unauthentica

Published Aug 14, 2025 · catalog updated Aug 14, 2025 · Cisco Cisco Adaptive Security Appliance (ASA) Software

Last checked Oct 24, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2025-20133. EPSS is 0.78%. Act only if a listed version of Cisco Cisco Adaptive Security Appliance (ASA) Software is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High8.6
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.78%
Remediation
Advisory link
Affected products
vendor Cisco Cisco Adaptive Security Appliance (ASA) Software 9.8.3.26

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 conditi

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor Cisco Cisco Adaptive Security Appliance (ASA) Software 9.8.3.269.8.3.26

How to fix CVE-2025-20133

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-20133. EPSS is 0.78%. Act only if a listed version of Cisco Cisco Adaptive Security Appliance (ASA) Software is installed.

Which versions are affected?

Compare what you have installed with Cisco Cisco Adaptive Security Appliance (ASA) Software 9.8.3.26 9.8.3.26. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.78%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Cisco security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Aug 14, 2025 · EUVD

    Detected

    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 authenti

  2. Aug 14, 2025 · EUVD

    Updated

    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 authenti

Sources

  • CVE.orgVulnerability recordCVE-2025-20133

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-20133

    30-day exploitation probability 0.78%

    first.org
  • EUVDVulnerability recordEUVD-2025-24855

    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 conditi

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Oct 24, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSOct 24, 2026
  • CVE.orgOct 21, 2026
  • EUVDOct 20, 2026