CVE-2026-20071 describes a vulnerability in Cisco ISE's BYOD onboarding workflow where insufficient authentication checks allow an unauthenticated, adjacent attacker to hijack another user's onboarding session. The attacker can spoof the legitimate user and cause redirection to the guest web portal, resulting in session takeover and access to protected 802.1X networks. The vulnerability is rated low severity with a CVSS 3.1 score of 3.8 (Attack Vector: Adjacent, Attack Complexity: Low, Privileges Required: None, User Interaction: Required, Scope: Changed, Confidentiality: None, Integrity: Low, Availability: None). No known exploits in the wild or vendor patches are indicated in the provided data.

An attacker who can exploit this vulnerability may hijack the onboarding session of another user and gain access to protected 802.1X networks. The impact is limited to integrity loss (session hijacking) without confidentiality or availability impact. The attack requires adjacency and user interaction (triggering redirection). No known active exploitation has been reported.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch information is provided in the available data. Until a patch is available, organizations should monitor vendor advisories for updates and consider restricting adjacency access to the onboarding network segment if feasible.