CVE-2026-20190: Cisco ISE Unauthenticated Remote Credential Access Vulnerability

Technical summary

CVE-2026-20190 is an improper authorization vulnerability (CWE-285) in Cisco ISE and ISE-PIC platforms. The root cause is insufficient authorization validation when resources are accessed over the network. An unauthenticated, remote attacker can trigger the flaw by sending malicious traffic to an affected device, bypassing authentication and authorization controls to gain read access to sensitive information. The CVSS 3.1 vector (7.5 HIGH: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) reflects network-accessible attack surface, low complexity, no privileges required, and high confidentiality impact with no integrity or availability compromise.

Business impact

This vulnerability poses a direct confidentiality risk to organizations relying on Cisco ISE for network access control and identity management. ISE typically holds critical authentication and authorization data, making credential exposure particularly dangerous. Attackers gaining access to hashed credentials could initiate offline cracking attempts, potentially compromising user accounts and gaining unauthorized network access. For organizations using ISE-PIC for passive network monitoring, the exposure of identity and traffic metadata could leak sensitive business information or user behavior patterns. The lack of authentication requirements means any attacker with network reach can attempt exploitation, significantly expanding the attack surface.

Affected systems

Multiple versions of Cisco Identity Services Engine (ISE) and Identity Services Engine-Passive Identity Connector (ISE-PIC) are affected. The vulnerability impacts both primary ISE deployment platforms and ISE-PIC instances used for passive identity collection and correlation. Organizations should consult Cisco's advisory to identify which specific firmware versions in their environment require patching, as the vulnerability spans multiple release trains.

Exploitability

This vulnerability is readily exploitable. The attack requires no authentication, no special user interaction, and minimal complexity—an attacker simply sends crafted traffic from any network-connected position. The low barrier to exploitation, combined with widespread ISE deployments in enterprise networks, creates substantial risk. The CVE is not currently listed in CISA's Known Exploited Vulnerabilities catalog, but the straightforward nature of the flaw and high-value nature of exposed credentials make active exploitation likely.

Remediation

Cisco has released security updates addressing this authorization bypass. Organizations must prioritize identifying all ISE and ISE-PIC instances in their environment and apply vendor patches. Interim mitigations should focus on network segmentation—restricting ISE administrative and API interfaces to trusted management networks and blocking untrusted external access where feasible. Monitor ISE logs for unusual resource access patterns or failed authorization attempts. Verify patch deployment by confirming updated firmware versions and re-testing access controls post-patch.

Patch guidance

Apply security updates from Cisco for Identity Services Engine and ISE-PIC as released by the vendor. Consult Cisco's official security advisory for specific version numbers and patch paths for your deployment model (cloud, on-premises, or hybrid). Prioritize patching ISE nodes that handle authentication for critical systems. Test patches in a non-production environment first to validate functionality and compatibility with your network policies and integrations. After patching, perform access control validation to ensure the authorization checks are functioning correctly.

Detection guidance

Monitor ISE access logs for unauthorized or anomalous resource access attempts, particularly unauthenticated requests to sensitive endpoints. Alert on failed authorization events that precede successful data retrieval, which may indicate exploitation attempts. Network-level detection should focus on identifying unexpected connections to ISE admin or API ports from untrusted sources. Inspect network traffic for malformed or suspicious requests targeting ISE REST APIs or web interfaces. Correlate any access to credential storage areas with user identity to identify suspicious patterns. Review ISE audit logs post-patch to establish a baseline for normal operations.

Why prioritize this

This vulnerability merits immediate attention due to its high CVSS score (7.5), unauthenticated remote exploitability, and direct exposure of sensitive credentials. ISE is a critical component of enterprise identity infrastructure; compromise of its data directly threatens network access controls and user authentication. The lack of complexity in exploitation and the high-value nature of potential compromise (hashed credentials for future attacks) make this a priority for urgent patching and validation.

Risk score, explained

The CVSS 3.1 score of 7.5 (HIGH) reflects a network-accessible vulnerability with no authentication or user interaction required, resulting in high confidentiality impact. The absence of integrity or availability impact prevents a CRITICAL rating, but the confidentiality component—exposure of hashed credentials and sensitive information—is substantial and directly impacts organizational security posture. The score appropriately balances ease of exploitation against the scope of potential damage.

Frequently asked questions