Cisco ASA/FTD AnyConnect SSL VPN DOS via Session Leak
CVE-2023-20042 Published on November 1, 2023

A vulnerability in the AnyConnect SSL VPN feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to an implementation error within the SSL/TLS session handling process that can prevent the release of a session handler under specific conditions. An attacker could exploit this vulnerability by sending crafted SSL/TLS traffic to an affected device, increasing the probability of session handler leaks. A successful exploit could allow the attacker to eventually deplete the available session handler pool, preventing new sessions from being established and causing a DoS condition.

NVD

Vulnerability Analysis

CVE-2023-20042 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
HIGH
Privileges Required:
NONE
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
HIGH

Weakness Type

Improper Resource Shutdown or Release

The program does not release or incorrectly releases a resource before it is made available for re-use. When a resource is created or allocated, the developer is responsible for properly releasing the resource as well as accounting for all potential paths of expiration or invalidation, such as a set period of time or revocation.


Products Associated with CVE-2023-20042

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Cisco Firepower Threat Defense
 
Cisco Adaptive Security Appliance Software
 
Cisco Adaptive Security Appliance
 

Affected Versions

Cisco Adaptive Security Appliance (ASA) Software: Cisco Firepower Threat Defense Software:

Exploit Probability

EPSS
0.25%
Percentile
48.32%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.