CVE-2025-20160: Cisco IOS

High severity, CVSS 8.1. EPSS: 0.4% chance of exploitation in the next 30 days.

A vulnerability in the implementation of the TACACS+ protocol in Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to view sensitive data or bypass authentication. This vulnerability exists because the system does not properly check whether the required TACACS+ shared secret is configured. A machine-in-the-middle attacker could exploit this vulnerability by intercepting and reading unencrypted TACACS+ messages or impersonating the TACACS+ server and falsely accepting arbitrary authentication requests. A successful exploit could allow the attacker to view sensitive information in a TACACS+ message or bypass authentication and gain access to the affected device.

Affected products

• Cisco IOS: version 15.2(4)e6 only; version 15.2(4)e7 only; version 15.2(4)e8 only; version 15.2(4)e9 only; version 15.2(4)e10 only; version 15.2(4)e10a only; …
• Cisco IOS XE: version 3.8.6e only; version 3.8.7e only; version 3.8.8e only; version 3.8.9e only; version 3.8.10e only; version 3.10.1e only; …

Published 2025-09-24. Last modified 2026-09-26.