CVE-2026-20352 Cisco Identity Services Engine RADIUS Denial of Service Vulnerability
Unauthenticated remote attackers can cause a denial of service on Cisco ISE by sending crafted RADIUS requests, blocking network access for unauthenticated endpoints.
- 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-2026-20352?
CVE-2026-20352 is a high-severity denial of service vulnerability in Cisco Identity Services Engine Software, published on 16 Sep 2026. 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 a denial of service (DoS) condition on an affected device. This vulnerability is due to improper handling of certain RADIUS requests. An attacker could exploit this vulnerability by sending a crafted RADIUS request directly to an affected device. A successful exploit could allow the attacker to cause the ISE node to become unavailable. For single node deployments in that condition, endpoints that have not already authenticated would be unable to access the network until the node comes back up on its own.
Weakness: CWE-119
Which versions are affected by CVE-2026-20352?
How do I fix CVE-2026-20352?
No fix has been published for CVE-2026-20352 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-2026-20352 being exploited?
There is no known exploitation of CVE-2026-20352 in the wild and no public exploit code.
Sources
Also known as GHSA-qwcp-547c-v9v8.