CVE-2023-20042

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

0.9% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2023-11-01 18:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-08-11 19:33 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.9% in the next 30 days (EPSS).
• Severity: 6.8 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2023-11-01 18:15 UTC

Last modified

2026-08-11 19:33 UTC

Exploit probability

0.9% · EPSS, next 30 days

Weakness

CWE-404

Record status

Modified

Affected

• Cisco Secure Firewall Threat Defense 7.0.0
• Cisco Secure Firewall Threat Defense 7.0.0.1
• Cisco Secure Firewall Threat Defense 7.0.1
• Cisco Secure Firewall Threat Defense 7.0.1.1
• Cisco Secure Firewall Threat Defense 7.0.2
• Cisco Secure Firewall Threat Defense 7.0.2.1
• Cisco Secure Firewall Threat Defense 7.0.3
• Cisco Secure Firewall Threat Defense 7.0.4

Attack profile CVSS 3.1 · 6.8

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Changed

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2023-20042.md and follow it. Check whether this project is affected by CVE-2023-20042. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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