Cisco ASA/FTD Authentication Bypass Using an Alternate Path or Channel (CVE-2023-20269)

critical Tenable OT Security Plugin ID 505550

Synopsis

The remote OT asset is affected by a vulnerability.

Description

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).

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.

Solution

Refer to the vendor advisory.

Plugin Details

Severity: Critical

ID: 505550

File Name: tenable_ot_cisco_CVE-2023-20269.nasl

Version: 1.3

Type: Remote

Family: Tenable.ot

Published: 7/20/2026

Updated: 7/21/2026

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: High

Score: 7.3

Percentile: 98.46

CVSS v2

Risk Factor: High

Base Score: 9.4

Temporal Score: 8.2

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:N

CVSS Score Source: CVE-2023-20269

CVSS v3

Risk Factor: Critical

Base Score: 9.1

Temporal Score: 8.7

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Temporal Vector: CVSS:3.0/E:H/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:cisco:adaptive_security_appliance_software, cpe:/o:cisco:firepower_threat_defense

Required KB Items: Tenable.ot/Cisco

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 9/6/2023

Vulnerability Publication Date: 9/6/2023

CISA Known Exploited Vulnerability Due Dates: 10/4/2023

Reference Information

CVE: CVE-2023-20269

CWE: 288

Detections

Analytics