CVE-2023-20240

What it is

Multiple vulnerabilities in Cisco Secure Client Software, formerly AnyConnect Secure Mobility Client, could allow an authenticated, local attacker to cause a denial of service (DoS) condition on an affected system. These vulnerabilities are due to an out-of-bounds memory read from Cisco Secure Client Software. An attacker could exploit these vulnerabilities by logging in to an affected device at the same time that another user is accessing Cisco Secure Client on the same system, and then sending crafted packets to a port on that local host. A successful exploit could allow the attacker to crash the VPN Agent service, causing it to be unavailable to all users of the system. To exploit these vulnerabilities, the attacker must have valid credentials on a multi-user system.

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. High risk of service disruption.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

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

Timeline

1. 2023-11-22 17:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 05:30 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 5.5 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2023-11-22 17:15 UTC

Last modified

2026-06-17 05:30 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-125 · Out-of-bounds read

Record status

Modified

Affected

• Cisco Anyconnect Secure Mobility Client 4.9.00086
• Cisco Anyconnect Secure Mobility Client 4.9.01095
• Cisco Anyconnect Secure Mobility Client 4.9.02028
• Cisco Anyconnect Secure Mobility Client 4.9.03047
• Cisco Anyconnect Secure Mobility Client 4.9.03049
• Cisco Anyconnect Secure Mobility Client 4.9.04043
• Cisco Anyconnect Secure Mobility Client 4.9.04053
• Cisco Anyconnect Secure Mobility Client 4.9.05042

Attack profile CVSS 3.1 · 5.5

Attack vector

Local

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

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-2023-20240.md and follow it. Check whether this project is affected by CVE-2023-20240. 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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