CVE-2025-20160
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA vulnerability in the TACACS+ protocol implementation in Cisco IOS/IOS XE Software allows an unauthenticated remote attacker to exploit the lack of proper validation for the TACACS+ shared secret configuration. An attacker can perform a MITM attack to read unencrypted TACACS+ messages or impersonate the TACACS+ server to accept arbitrary authentication requests, enabling sensitive information disclosure or complete authentication bypass.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Verify device is running Cisco IOS or IOS XEUse the 'show version' command to confirm the device is running Cisco IOS or IOS XE software.Affected if Device runs any version of Cisco IOS or IOS XE.
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Check if TACACS+ is enabled on the deviceRun 'show tacacs' or inspect the running configuration with 'show running-config | include tacacs' to determine if TACACS+ is configured.Affected if TACACS+ is configured and enabled on the device.
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Verify TACACS+ server configurationRun 'show tacacs server' or check the TACACS+ server group configuration to identify configured servers and their settings.Affected if TACACS+ servers are configured.
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Inspect TACACS+ shared secret configurationReview the TACACS+ key configuration using 'show running-config | include tacacs' or the specific TACACS server group configuration. Look for the 'key' or 'key-string' settings.Affected if The TACACS+ shared secret is weak, missing, or the key configuration is improperly set.
The device is affected if it runs Cisco IOS/IOS XE with TACACS+ enabled and the shared secret is weak, missing, or not properly configured, allowing potential MITM attacks.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataEnsure a strong TACACS+ shared secret is properly configured on the device and consider implementing additional network-layer protections (VPNs, network segmentation) to prevent MITM attacks on TACACS+ traffic.
- Consultation4.0 h
- Implementation3.0 h
- Testing4.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2025-20160 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-20160 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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