---
id: CVE-2025-20160
title: >-
  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
summary: "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. \r\n\r This vulnerability exists …"
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-287
vendor: cisco
product: ios
affected:
  - ios = 15.2(4)e6
  - ios = 15.2(4)e7
  - ios = 15.2(4)e8
  - ios = 15.2(4)e9
  - ios = 15.2(4)e10
  - ios = 15.2(4)e10a
  - ios = 15.2(4)e10d
  - ios = 15.2(6)e1
  - ios = 15.2(6)e2
  - ios = 15.2(6)e2a
  - ios = 15.2(6)e2b
  - ios = 15.2(6)e3
  - ios = 15.2(6)eb
  - ios = 15.2(7)e
  - ios = 15.2(7)e0a
  - ios = 15.2(7)e0b
  - ios = 15.2(7)e0s
  - ios = 15.2(7)e1
  - ios = 15.2(7)e1a
  - ios = 15.2(7)e2
  - ios = 15.2(7)e2a
  - ios = 15.2(7)e3
  - ios = 15.2(7)e3k
  - ios = 15.2(7)e4
  - ios = 15.2(7)e5
  - ios = 15.2(7)e6
  - ios = 15.2(7)e7
  - ios = 15.2(7)e8
  - ios = 15.2(7)e9
  - ios = 15.2(7)e10
  - ios = 15.2(7)e11
  - ios = 15.2(7)e12
  - ios = 15.2(7a)e0b
  - ios = 15.2(7b)e0b
  - ios = 15.2(8)e
  - ios = 15.2(8)e1
  - ios = 15.2(8)e2
  - ios = 15.2(8)e3
  - ios = 15.2(8)e4
  - ios = 15.2(8)e5
  - ios = 15.2(8)e6
  - ios = 15.2(8)e7
  - ios = 15.5(1)sy2
  - ios = 15.5(1)sy3
  - ios = 15.5(1)sy4
  - ios = 15.5(1)sy5
  - ios = 15.5(1)sy6
  - ios = 15.5(1)sy7
  - ios = 15.5(1)sy8
  - ios = 15.5(1)sy9
  - ios = 15.5(1)sy10
  - ios = 15.5(1)sy11
  - ios = 15.5(1)sy12
  - ios = 15.5(1)sy13
  - ios = 15.5(1)sy14
  - ios = 15.5(1)sy15
  - ios = 15.5(3)m7
  - ios = 15.5(3)m8
  - ios = 15.5(3)m9
  - ios = 15.5(3)m10
  - ios = 15.5(3)s8
  - ios = 15.5(3)s9
  - ios = 15.5(3)s9a
  - ios = 15.5(3)s10
  - ios = 15.6(2)sp5
  - ios = 15.6(2)sp6
  - ios = 15.6(2)sp7
  - ios = 15.6(2)sp8
  - ios = 15.6(2)sp9
  - ios = 15.6(3)m4
  - ios = 15.6(3)m5
  - ios = 15.6(3)m6
  - ios = 15.6(3)m6a
  - ios = 15.6(3)m6b
  - ios = 15.6(3)m7
  - ios = 15.6(3)m8
  - ios = 15.6(3)m9
  - ios = 15.7(3)m2
  - ios = 15.7(3)m3
  - ios = 15.7(3)m4
  - ios = 15.7(3)m4a
  - ios = 15.7(3)m4b
  - ios = 15.7(3)m5
  - ios = 15.7(3)m6
  - ios = 15.7(3)m7
  - ios = 15.7(3)m8
  - ios = 15.7(3)m9
  - ios = 15.8(3)m
  - ios = 15.8(3)m0a
  - ios = 15.8(3)m0b
  - ios = 15.8(3)m1
  - ios = 15.8(3)m1a
  - ios = 15.8(3)m2
  - ios = 15.8(3)m2a
  - ios = 15.8(3)m3
  - ios = 15.8(3)m3a
  - ios = 15.8(3)m3b
  - ios = 15.8(3)m4
  - ios = 15.8(3)m5
  - ios = 15.8(3)m6
published: '2025-09-24'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T13:18:38.953'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-20160'
references:
  - url: >-
      https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-tacacs-hdB7thJw
    label: psirt@cisco.com
tags:
  - nvd
epss: 0.00432
epssPercentile: 0.37071
ingestedAt: '2026-09-18T12:40:48.881Z'
---

## Overview

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

- `ios = 15.2(4)e6`
- `ios = 15.2(4)e7`
- `ios = 15.2(4)e8`
- `ios = 15.2(4)e9`
- `ios = 15.2(4)e10`
- `ios = 15.2(4)e10a`
- `ios = 15.2(4)e10d`
- `ios = 15.2(6)e1`
- `ios = 15.2(6)e2`
- `ios = 15.2(6)e2a`
- `ios = 15.2(6)e2b`
- `ios = 15.2(6)e3`
- `ios = 15.2(6)eb`
- `ios = 15.2(7)e`
- `ios = 15.2(7)e0a`
- `ios = 15.2(7)e0b`
- `ios = 15.2(7)e0s`
- `ios = 15.2(7)e1`
- `ios = 15.2(7)e1a`
- `ios = 15.2(7)e2`
- `ios = 15.2(7)e2a`
- `ios = 15.2(7)e3`
- `ios = 15.2(7)e3k`
- `ios = 15.2(7)e4`
- `ios = 15.2(7)e5`
- `ios = 15.2(7)e6`
- `ios = 15.2(7)e7`
- `ios = 15.2(7)e8`
- `ios = 15.2(7)e9`
- `ios = 15.2(7)e10`
- `ios = 15.2(7)e11`
- `ios = 15.2(7)e12`
- `ios = 15.2(7a)e0b`
- `ios = 15.2(7b)e0b`
- `ios = 15.2(8)e`
- `ios = 15.2(8)e1`
- `ios = 15.2(8)e2`
- `ios = 15.2(8)e3`
- `ios = 15.2(8)e4`
- `ios = 15.2(8)e5`
- `ios = 15.2(8)e6`
- `ios = 15.2(8)e7`
- `ios = 15.5(1)sy2`
- `ios = 15.5(1)sy3`
- `ios = 15.5(1)sy4`
- `ios = 15.5(1)sy5`
- `ios = 15.5(1)sy6`
- `ios = 15.5(1)sy7`
- `ios = 15.5(1)sy8`
- `ios = 15.5(1)sy9`
- `ios = 15.5(1)sy10`
- `ios = 15.5(1)sy11`
- `ios = 15.5(1)sy12`
- `ios = 15.5(1)sy13`
- `ios = 15.5(1)sy14`
- `ios = 15.5(1)sy15`
- `ios = 15.5(3)m7`
- `ios = 15.5(3)m8`
- `ios = 15.5(3)m9`
- `ios = 15.5(3)m10`
- `ios = 15.5(3)s8`
- `ios = 15.5(3)s9`
- `ios = 15.5(3)s9a`
- `ios = 15.5(3)s10`
- `ios = 15.6(2)sp5`
- `ios = 15.6(2)sp6`
- `ios = 15.6(2)sp7`
- `ios = 15.6(2)sp8`
- `ios = 15.6(2)sp9`
- `ios = 15.6(3)m4`
- `ios = 15.6(3)m5`
- `ios = 15.6(3)m6`
- `ios = 15.6(3)m6a`
- `ios = 15.6(3)m6b`
- `ios = 15.6(3)m7`
- `ios = 15.6(3)m8`
- `ios = 15.6(3)m9`
- `ios = 15.7(3)m2`
- `ios = 15.7(3)m3`
- `ios = 15.7(3)m4`
- `ios = 15.7(3)m4a`
- `ios = 15.7(3)m4b`
- `ios = 15.7(3)m5`
- `ios = 15.7(3)m6`
- `ios = 15.7(3)m7`
- `ios = 15.7(3)m8`
- `ios = 15.7(3)m9`
- `ios = 15.8(3)m`
- `ios = 15.8(3)m0a`
- `ios = 15.8(3)m0b`
- `ios = 15.8(3)m1`
- `ios = 15.8(3)m1a`
- `ios = 15.8(3)m2`
- `ios = 15.8(3)m2a`
- `ios = 15.8(3)m3`
- `ios = 15.8(3)m3a`
- `ios = 15.8(3)m3b`
- `ios = 15.8(3)m4`
- `ios = 15.8(3)m5`
- `ios = 15.8(3)m6`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.