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Ios Xe Sd WanOperating system · Cisco

CVE-2021-34725

MEDIUM · 6.7 CVSS v3.1 Published 2021-09-23
Fix available
A fix is available. Upgrade to after 17.2.1r or later.
See remediation →
69/100
Remediation priority · Elevated
Zero-click

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 · unedited
A vulnerability in the CLI of Cisco IOS XE SD-WAN Software could allow an authenticated, local attacker to inject arbitrary commands to be executed with root-level privileges on the underlying operating system. This vulnerability is due to insufficient input validation on certain CLI commands. An attacker could exploit this vulnerability by authenticating to an affected device and submitting crafted input to the CLI. The attacker must be authenticated as an administrative user to execute the affected commands. A successful exploit could allow the attacker to execute commands with root-level privileges.

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 confidence

Command injection vulnerability in Cisco IOS XE SD-WAN CLI where insufficient input validation on certain CLI commands allows an authenticated administrative user to inject arbitrary OS commands that execute with root-level privileges.

MitigationApply Cisco's security patch for this vulnerability. Ensure proper access controls and monitor for any unauthorized administrative access to affected devices.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Ios Xe Sd WanOperating system
Affected:<= 17.2.1r

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
Local
Complexity
Low
Privileges
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:H/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify the IOS XE version
    Run 'show version' or 'show version | include Version' command on the device CLI to determine the installed IOS XE version number
    Affected if The displayed version is 17.2.1r or any earlier version (17.2.1, 17.1.x, etc.)
  2. Confirm SD-WAN is enabled
    Run 'show sdwan version' or check the configuration for 'sdwan' related CLI commands and processes using 'show process cpu history' or reviewing the running configuration
    Affected if SD-WAN features or processes are active on the device
  3. Check for admin access to SD-WAN CLI
    Review user accounts with privilege level 15 (administrative access) and check if they have access to the SD-WAN CLI interface. Use 'show users' and review AAA configuration with 'show running-config | include aaa'
    Affected if Any user account with administrative privileges can access the SD-WAN CLI interface, making the device potentially exploitable by anyone with admin credentials
  4. Review logs for suspicious CLI activity
    Check system logs, AAA logging, and command history using 'show logging' or 'show archive log config all' for unexpected or malformed SD-WAN CLI commands that may indicate exploitation attempts
    Affected if Any logged SD-WAN CLI commands containing unusual characters or patterns that suggest command injection attempts are present

The device is affected if it runs Cisco IOS XE with SD-WAN enabled at version 17.2.1r or earlier and has administrative users who can access the SD-WAN CLI interface.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Upgrade available Upgrade to a release after 17.2.1r
Interim mitigation

Apply Cisco's security patch for this vulnerability. Ensure proper access controls and monitor for any unauthorized administrative access to affected devices.

Fix this in Ios Xe Sd Wan Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,408.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-34725 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data