Cisco ASA Improper Resource Shutdown or Release (CVE-2023-20042)

high Tenable OT Security Plugin ID 506052

Synopsis

The remote OT asset is affected by a vulnerability.

Description

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.

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: High

ID: 506052

File Name: tenable_ot_cisco_CVE-2023-20042.nasl

Version: 1.2

Type: Remote

Family: Tenable.ot

Published: 10/5/2026

Updated: 10/6/2026

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Low

Score: 3.3

Percentile: 50.87

CVSS v2

Risk Factor: High

Base Score: 7.8

Temporal Score: 5.8

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

CVSS Score Source: CVE-2023-20042

CVSS v3

Risk Factor: High

Base Score: 8.6

Temporal Score: 7.5

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

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

Vulnerability Information

CPE: cpe:/o:cisco:adaptive_security_appliance_software:9.16.1.28, cpe:/o:cisco:adaptive_security_appliance_software:9.16.1, cpe:/o:cisco:adaptive_security_appliance_software:9.16.2.11, cpe:/o:cisco:adaptive_security_appliance_software:9.16.2.13, cpe:/o:cisco:adaptive_security_appliance_software:9.16.2.14, cpe:/o:cisco:adaptive_security_appliance_software:9.16.2.3, cpe:/o:cisco:adaptive_security_appliance_software:9.16.2.7, cpe:/o:cisco:adaptive_security_appliance_software:9.16.2, cpe:/o:cisco:adaptive_security_appliance_software:9.16.3.14, cpe:/o:cisco:adaptive_security_appliance_software:9.16.3.15, cpe:/o:cisco:adaptive_security_appliance_software:9.16.3.19, cpe:/o:cisco:adaptive_security_appliance_software:9.16.3.23, cpe:/o:cisco:adaptive_security_appliance_software:9.16.3.3, cpe:/o:cisco:adaptive_security_appliance_software:9.16.3, cpe:/o:cisco:adaptive_security_appliance_software:9.16.4.9, cpe:/o:cisco:adaptive_security_appliance_software:9.16.4, cpe:/o:cisco:adaptive_security_appliance_software:9.17.1.10, cpe:/o:cisco:adaptive_security_appliance_software:9.17.1.11, cpe:/o:cisco:adaptive_security_appliance_software:9.17.1.13, cpe:/o:cisco:adaptive_security_appliance_software:9.17.1.15, cpe:/o:cisco:adaptive_security_appliance_software:9.17.1.20, cpe:/o:cisco:adaptive_security_appliance_software:9.17.1.7, cpe:/o:cisco:adaptive_security_appliance_software:9.17.1.9, cpe:/o:cisco:adaptive_security_appliance_software:9.17.1, cpe:/o:cisco:adaptive_security_appliance_software:9.18.1.3, cpe:/o:cisco:adaptive_security_appliance_software:9.18.1, cpe:/o:cisco:adaptive_security_appliance_software:9.18.2.5, cpe:/o:cisco:adaptive_security_appliance_software:9.18.2.7, cpe:/o:cisco:adaptive_security_appliance_software:9.18.2, cpe:/o:cisco:adaptive_security_appliance_software:9.19.1

Required KB Items: Tenable.ot/Cisco

Exploit Ease: No known exploits are available

Patch Publication Date: 11/1/2023

Vulnerability Publication Date: 11/1/2023

Reference Information

CVE: CVE-2023-20042

CWE: 404

Detections

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