CVE-2023-20243 Denial of service in Cisco Identity Services Engine Software
Unauthenticated remote attackers can cause Cisco ISE to stop processing RADIUS packets, denying network access to legitimate users.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2023-20243?
CVE-2023-20243 is a high-severity denial of service vulnerability in Cisco Identity Services Engine, published on 6 Sep 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability in the RADIUS message processing feature of Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to cause the affected system to stop processing RADIUS packets. This vulnerability is due to improper handling of certain RADIUS accounting requests. An attacker could exploit this vulnerability by sending a crafted authentication request to a network access device (NAD) that uses Cisco ISE for authentication, authorization, and accounting (AAA). This would eventually result in the NAD sending a RADIUS accounting request packet to Cisco ISE. An attacker could also exploit this vulnerability by sending a crafted RADIUS accounting request packet to Cisco ISE directly if the RADIUS shared secret is known. A successful exploit could allow the attacker to cause the RADIUS process to unexpectedly restart, resulting in authentication or authorization timeouts and denying legitimate users access to the network or service. Clients already authenticated to the network would not be affected. Note: To recover the ability to process RADIUS packets, a manual restart of the affected Policy Service Node (PSN) may be required. For more information, see the Details ["#details"] section of this advisory.
Which versions are affected by CVE-2023-20243?
It affects 1 product.
Products include Cisco Identity Services Engine.
How do I fix CVE-2023-20243?
No fix has been published for CVE-2023-20243 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-2023-20243 being exploited?
There is no known exploitation of CVE-2023-20243 in the wild and no public exploit code.
Other vulnerabilities in Cisco Identity Services Engine
- CVE-2026-76460 Cisco Identity Services Engine Incorrect Use of Privileged APIs
- CVE-2025-20337 Cisco Identity Services Engine Injection
- CVE-2025-20281 Cisco Identity Services Engine Injection
- CVE-2026-20130 Cisco Identity Services Engine Hardening Release - Improper Neutralization Vulnerabilities
- CVE-2026-20192 Cisco Identity Services Engine Hardening Release - Access Control Vulnerabilities
Sources
Also known as GHSA-64jj-6hmj-39jw.