Cisco Identity Services Engine up to 3.5.0 RADIUS feature denial of service

Summaryinfo

A vulnerability has been found in Cisco Identity Services Engine up to 3.5.0 and classified as critical. This affects an unknown function of the component RADIUS feature. Performing a manipulation results in denial of service. This vulnerability is reported as CVE-2026-20352. The attack is possible to be carried out remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as critical, was found in Cisco Identity Services Engine up to 3.5.0. This affects an unknown part of the component RADIUS feature. The manipulation with an unknown input leads to a denial of service vulnerability. CWE is classifying the issue as CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. This is going to have an impact on availability. The summary by CVE is:

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.

It is possible to read the advisory at sec.cloudapps.cisco.com. This vulnerability is uniquely identified as CVE-2026-20352 since 10/08/2025. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/16/2026). The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading eliminates this vulnerability.

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Productinfo

Type

• Policy Management Software

Vendor

• Cisco

Name

• Identity Services Engine

Version

• 3.2.0
• 3.2.0 p1
• 3.2.0 p2
• 3.2.0 p3
• 3.2.0 p4
• 3.2.0 p5
• 3.2.0 p6
• 3.2.0 p7
• 3.3.0
• 3.4.0
• 3.5.0

License

• commercial

Website

• Vendor: https://www.cisco.com/

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