CVE-2023-20269
MEDIUMCISA KEVEPSS 97th pctlDescription
A vulnerability in the remote access VPN feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to conduct a brute force attack in an attempt to identify valid username and password combinations or an authenticated, remote attacker to establish a clientless SSL VPN session with an unauthorized user. This vulnerability is due to improper separation of authentication, authorization, and accounting (AAA) between the remote access VPN feature and the HTTPS management and site-to-site VPN features. An attacker could exploit this vulnerability by specifying a default connection profile/tunnel group while conducting a brute force attack or while establishing a clientless SSL VPN session using valid credentials. A successful exploit could allow the attacker to achieve one or both of the following: Identify valid credentials that could then be used to establish an unauthorized remote access VPN session. Establish a clientless SSL VPN session (only when running Cisco ASA Software Release 9.16 or earlier). Notes: Establishing a client-based remote access VPN tunnel is not possible as these default connection profiles/tunnel groups do not and cannot have an IP address pool configured. This vulnerability does not allow an attacker to bypass authentication. To successfully establish a remote access VPN session, valid credentials are required, including a valid second factor if multi-factor authentication (MFA) is configured. Cisco will release software updates that address this vulnerability. There are workarounds that address this vulnerability.
How to fix
Actively exploited, no published fix found yet
CISA required action: Apply mitigations per vendor instructions for group-lock and vpn-simultaneous-logins or discontinue use of the product for unsupported devices.
Federal remediation due: 2023-10-04
Known ransomware campaign use
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N
Exploit Intelligence
Very high risk: more likely to be exploited than 97% of all known CVEs.
Cisco Adaptive Security Appliance and Firepower Threat Defense Unauthorized Access Vulnerability
Cisco Adaptive Security Appliance and Firepower Threat Defense contain an unauthorized access vulnerability that could allow an unauthenticated, remote attacker to conduct a brute force attack in an attempt to identify valid username and password combinations or establish a clientless SSL VPN session with an unauthorized user.
Apply mitigations per vendor instructions for group-lock and vpn-simultaneous-logins or discontinue use of the product for unsupported devices.
Remediation due: 2023-10-04
Associated with ransomware campaigns
References
Related Vulnerabilities
Other CWE-288 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2023-42793 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2024-1709 | Critical | 10.0 | 100% | KEV + Ransom | Fix |
| CVE-2024-27198 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2025-4427 | Medium | 5.3 | 100% | KEV | Fix |
| CVE-2024-55591 | Critical | 9.8 | 98% | KEV + Ransom | Fix |
| CVE-2023-46747 | Critical | 9.8 | 97% | KEV + Ransom | - |
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-10-28.