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.

The WebVPN implementation on Cisco Adaptive Security Appliances (ASA) 5500 series devices with software before 8.2(3) permits the viewing of CIFS shares even when CIFS file browsing has been disabled, which allows remote authenticated users to bypass intended access restrictions via CIFS requests, aka Bug ID CSCsz80777.

Cisco Adaptive Security Appliances (ASA) 5500 series devices with software before 8.2(3) do not properly determine the interfaces for which TELNET connections should be permitted, which allows remote authenticated users to bypass intended access restrictions via vectors involving the "lowest security level interface," aka Bug ID CSCsv40504.

Buffer overflow in the Cisco Port Forwarder ActiveX control in cscopf.ocx, as distributed through the Clientless VPN feature on Cisco Adaptive Security Appliances (ASA) 5500 series devices with software 7.0 through 7.2 before 7.2(5.6), 8.0 before 8.0(5.26), 8.1 before 8.1(2.53), 8.2 before 8.2(5.18), 8.3 before 8.3(2.28), 8.2 before 8.4(2.16), and 8.6 before 8.6(1.1), allows remote attackers to execute arbitrary code via unspecified vectors, aka Bug ID CSCtr00165.

Buffer overflow in the IKEv1 and IKEv2 implementations in Cisco ASA Software before 8.4(7.30), 8.7 before 8.7(1.18), 9.0 before 9.0(4.38), 9.1 before 9.1(7), 9.2 before 9.2(4.5), 9.3 before 9.3(3.7), 9.4 before 9.4(2.4), and 9.5 before 9.5(2.2) on ASA 5500 devices, ASA 5500-X devices, ASA Services Module for Cisco Catalyst 6500 and Cisco 7600 devices, ASA 1000V devices, Adaptive Security Virtual Appliance (aka ASAv), Firepower 9300 ASA Security Module, and ISA 3000 devices allows remote attackers to execute arbitrary code or cause a denial of service (device reload) via crafted UDP packets, aka Bug IDs CSCux29978 and CSCux42019.