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.
| Software | From | Fixed in |
|---|---|---|
| cisco / identity_services_engine | 3.1 | 3.1.x |
| cisco / identity_services_engine | 3.1-patch1 | 3.1-patch1.x |
| cisco / identity_services_engine | 3.1-patch2 | 3.1-patch2.x |
| cisco / identity_services_engine | 3.1-patch3 | 3.1-patch3.x |
| cisco / identity_services_engine | 3.2 | 3.2.x |
| cisco / identity_services_engine | 3.1-patch4 | 3.1-patch4.x |
| cisco / identity_services_engine | 3.1-patch5 | 3.1-patch5.x |
| cisco / identity_services_engine | 3.2-patch1 | 3.2-patch1.x |
| cisco / identity_services_engine | 3.1-patch6 | 3.1-patch6.x |
| cisco / identity_services_engine | 3.2-patch2 | 3.2-patch2.x |
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.