SB2025092459 - Authentication bypass in Cisco IOS and IOS XE Software TACACS+ implementation

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Main Vulnerability Database SB2025092459

SB2025092459 - Authentication bypass in Cisco IOS and IOS XE Software TACACS+ implementation

Published: September 24, 2025

Security Bulletin ID SB2025092459
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Data manipulation

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Improper authentication (CVE-ID: CVE-2025-20160)

CWE-ID: CWE-287 - Improper Authentication

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Green


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.

References