CVE-2026-20285: Cisco ISE Auth Bypass Vulnerability

CVE-2026-20285 Overview

Cisco disclosed CVE-2026-20285, an authorization bypass vulnerability in the web-based management interface of Cisco Identity Services Engine (ISE) and Cisco ISE Passive Identity Connector (ISE-PIC). An authenticated remote attacker with valid Administrator credentials can modify parts of the device configuration by submitting a crafted HTTP request. The flaw stems from missing server-side validation of Administrator permissions, categorized under CWE-285 (Improper Authorization). Successful exploitation allows the attacker to alter file descriptions on a specific page within the management interface.

Critical Impact
An authenticated administrator with limited permissions can bypass role-based access controls to modify configuration elements they should not have permission to change.

Affected Products

Cisco Identity Services Engine (ISE)
Cisco ISE Passive Identity Connector (ISE-PIC)
Refer to the Cisco Security Advisory for specific fixed versions

Discovery Timeline

2026-09-16 - CVE-2026-20285 published to the National Vulnerability Database
2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-20285

Vulnerability Analysis

CVE-2026-20285 is an authorization bypass in the Cisco ISE and ISE-PIC web-based management interface. The affected endpoint accepts HTTP requests that modify file descriptions on a specific administrative page. The server processes these requests without confirming that the authenticated user holds the required Administrator permissions for the action. As a result, a lower-privileged administrator, or one with a restricted role, can perform configuration changes reserved for higher-privileged users. The impact is limited to integrity of specific configuration data, with no direct effect on confidentiality or availability.

Root Cause

The root cause is the absence of server-side authorization checks on a configuration modification endpoint. The application relies on client-side or session-level authentication without enforcing a granular permission check for the requested action. This maps to CWE-285: Improper Authorization, where the software performs an authorization check that does not correctly verify the actor's permission to perform the requested action.

Attack Vector

Exploitation requires network access to the ISE or ISE-PIC web interface and valid Administrator credentials. The attacker crafts an HTTP request targeting the vulnerable configuration endpoint and submits it directly to the interface. No user interaction is required. Because valid credentials are needed, the attack is most relevant in scenarios involving credential theft, insider misuse, or lateral movement following an initial compromise.

No public proof-of-concept code has been published for this vulnerability. Consult the Cisco Security Advisory for authoritative technical details.

Detection Methods for CVE-2026-20285

Indicators of Compromise

Unexpected modifications to file description fields on ISE or ISE-PIC administrative pages
Administrator-level HTTP POST or PUT requests originating from accounts that should not have configuration modification rights
Configuration change audit entries attributed to lower-privileged administrator accounts

Detection Strategies

Enable and review Cisco ISE administrative audit logs for configuration change events, correlating each change against the acting account's assigned role
Baseline the expected set of administrators authorized to modify configuration and alert on deviations
Forward ISE syslog and audit data to a centralized log platform for retention and correlation with authentication events

Monitoring Recommendations

Monitor authentication events for Administrator accounts, including source IP, session duration, and geographic anomalies
Track HTTP requests to the ISE management interface for unusual URI patterns or repeated configuration modification attempts
Alert on administrative session activity outside business hours or from previously unseen network locations

How to Mitigate CVE-2026-20285

Immediate Actions Required

Apply the fixed software release listed in the Cisco Security Advisory
Audit all ISE and ISE-PIC Administrator accounts and remove unnecessary or dormant credentials
Rotate credentials for all Administrator accounts, especially any shared or service accounts
Restrict network access to the ISE web management interface to trusted management networks only

Patch Information

Cisco has published a security advisory tracking this vulnerability. Administrators should consult the Cisco Security Advisory: ISE Auth Bypass to identify affected releases and the corresponding fixed software versions for their deployment.

Workarounds

No official workarounds are documented; upgrading to a fixed release is the recommended remediation
Enforce the principle of least privilege by limiting the number of accounts granted full Administrator rights
Require multi-factor authentication for all administrative access to ISE and ISE-PIC
Segment the management network so the web interface is unreachable from general user or guest networks

bash

# Configuration example: restrict management access via ACL
# Refer to the Cisco Security Advisory for authoritative guidance
access-list MGMT_ACCESS permit tcp <trusted_mgmt_subnet> host <ise_mgmt_ip> eq 443
access-list MGMT_ACCESS deny tcp any host <ise_mgmt_ip> eq 443