SB2025092459 - Authentication bypass in Cisco IOS and IOS XE Software TACACS+ implementation
Published: September 24, 2025
Security Bulletin ID
SB2025092459
Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Data manipulation
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 security vulnerability.
1) Improper authentication (CVE-ID: CVE-2025-20160)
The vulnerability allows a remote attacker to bypass authentication process.
The vulnerability exists due to an error in the implementation of the TACACS+ protocol where the system does not properly check whether the required TACACS+ shared secret was configured. A remote machine-in-the-middle attacker can read unencrypted TACACS+ messages or impersonate the TACACS+ server and falsely accept arbitrary authentication requests, leading to information disclosure.
Remediation
Install update from vendor's website.