CVE-2023-20213 Denial of service in Cisco Identity Services Engine Software

Medium 4.3 Published 1 Nov 2023 Updated 12 Jun 2025

An unauthenticated adjacent attacker can crash the CDP process on Cisco ISE by sending crafted traffic, requiring manual restart to restore neighbor discovery.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2023-20213?

CVE-2023-20213 is a medium-severity denial of service vulnerability in Cisco Identity Services Engine, published on 1 Nov 2023. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A vulnerability in the CDP processing feature of Cisco ISE could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition of the CDP process on an affected device. This vulnerability is due to insufficient bounds checking when an affected device processes CDP traffic. An attacker could exploit this vulnerability by sending crafted CDP traffic to the device. A successful exploit could cause the CDP process to crash, impacting neighbor discovery and the ability of Cisco ISE to determine the reachability of remote devices. After a crash, the CDP process must be manually restarted using the cdp enable command in interface configuration mode.

Weakness: CWE-787

Which versions are affected by CVE-2023-20213?

It affects 1 product.

Products include Cisco Identity Services Engine.

How do I fix CVE-2023-20213?

No fix has been published for CVE-2023-20213 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2023-20213 being exploited?

There is no known exploitation of CVE-2023-20213 in the wild and no public exploit code.

All Cisco Identity Services Engine vulnerabilities

Sources

Also known as GHSA-wrrj-56x5-rfqr.