Is CVE-2025-20133 actively exploited?

No active exploitation of CVE-2025-20133 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2025-20133 be exploited remotely?

Yes. CVE-2025-20133 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2025-20133?

CVE-2025-20133 has a CVSS score of 8.6 (HIGH).

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HIGH

CVE-2025-20133

CWE-401Published: August 14, 2025· Updated: Jun 17, 2026

8.6

CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2025-20133 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 8.6.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.