CVE-2025-20264 is a medium-severity vulnerability affecting Cisco Identity Services Engine (ISE) software versions ranging from 3.0.0 through various patches up to 3.4 Patch 1. The vulnerability resides in the web-based management interface of Cisco ISE, specifically related to improper authorization enforcement for users authenticated via SAML Single Sign-On (SSO) integration with external identity providers. An authenticated remote attacker who has legitimate access to the system can exploit this flaw by submitting crafted commands that bypass the intended authorization controls for certain administrative functions. This bypass allows the attacker to modify a limited subset of system settings, including those that can trigger a system restart. In single-node Cisco ISE deployments, such a restart can cause a denial of service for network authentication, as devices not yet authenticated will be unable to authenticate until the ISE system is back online. The vulnerability does not impact confidentiality but affects integrity and availability, as unauthorized changes can be made and system availability can be disrupted. The CVSS 3.1 base score is 6.4 (medium), with an attack vector of network (remote), low attack complexity, requiring privileges (authenticated user), no user interaction, and scope change due to impact on system availability beyond the vulnerable component. No known exploits are currently reported in the wild, but the vulnerability poses a risk especially in environments relying heavily on Cisco ISE for network access control and authentication.

For European organizations, the impact of this vulnerability can be significant, particularly for enterprises and service providers that use Cisco ISE for centralized network access control and policy enforcement. Unauthorized modification of administrative settings could lead to disruption of network authentication services, causing downtime or degraded network access for employees and devices. This is especially critical in single-node deployments where a system restart triggered by exploitation can result in temporary denial of network access, impacting business continuity. While confidentiality is not directly compromised, the integrity of system configurations is at risk, potentially allowing attackers to weaken security policies or disrupt operations. Critical infrastructure sectors such as finance, healthcare, telecommunications, and government agencies in Europe that rely on Cisco ISE for secure network access could face operational disruptions and increased risk of lateral movement by attackers if this vulnerability is exploited. The medium severity rating suggests that while exploitation requires authenticated access, the ease of bypassing authorization controls and the potential for availability impact make this a notable threat to network security posture.

1. Immediate patching: Organizations should prioritize applying Cisco’s security updates and patches for Cisco ISE versions affected by this vulnerability as soon as they become available. 2. Restrict SAML SSO user privileges: Limit the number of users authenticated via SAML SSO with administrative privileges and enforce the principle of least privilege to reduce the attack surface. 3. Monitor administrative activities: Implement enhanced logging and monitoring of administrative commands and configuration changes within Cisco ISE to detect anomalous or unauthorized actions promptly. 4. Network segmentation: Isolate Cisco ISE management interfaces from general network access, restricting access only to trusted administrative hosts and networks. 5. Multi-factor authentication (MFA): Enforce MFA for all administrative access to Cisco ISE to reduce the risk of compromised credentials being used to exploit this vulnerability. 6. Deploy high-availability (HA) configurations: Where possible, avoid single-node deployments by implementing HA clusters to mitigate the impact of system restarts and maintain continuous authentication services. 7. Conduct regular security audits: Periodically review Cisco ISE configurations, especially SAML SSO integration settings, to ensure authorization policies are correctly enforced and no unauthorized privilege escalations are possible.