CVE-2022-20756 Cisco Identity Services Engine RADIUS Service Denial of Service Vulnerability
Unauthenticated remote attackers can cause Cisco ISE to stop processing RADIUS requests, denying legitimate access until a manual restart.
- 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-2022-20756?
CVE-2022-20756 is a high-severity denial of service vulnerability in Cisco Identity Services Engine, published on 6 Apr 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability in the RADIUS 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 requests. An attacker could exploit this vulnerability by attempting to authenticate to a network or a service where the access server is using Cisco ISE as the RADIUS server. A successful exploit could allow the attacker to cause Cisco ISE to stop processing RADIUS requests, causing authentication/authorization timeouts, which would then result in legitimate requests being denied access. Note: To recover the ability to process RADIUS packets, a manual restart of the affected Policy Service Node (PSN) is required. See the Details section for more information.
Weakness: CWE-399
Which versions are affected by CVE-2022-20756?
It affects 1 product.
Products include Cisco Identity Services Engine.
How do I fix CVE-2022-20756?
No fix has been published for CVE-2022-20756 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-2022-20756 being exploited?
There is no known exploitation of CVE-2022-20756 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-qwcc-f7fm-5q6x.