dbcve.org
Ios XeOperating system · Cisco

CVE-2021-1443

HIGH · 7.2 CVSS v3.1 Published 2021-03-24
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
78/100
Remediation priority · High
Remotely reachable 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 web UI of Cisco IOS XE Software could allow an authenticated, remote attacker to execute arbitrary code with root privileges on the underlying operating system of an affected device. The vulnerability exists because the affected software improperly sanitizes values that are parsed from a specific configuration file. An attacker could exploit this vulnerability by tampering with a specific configuration file and then sending an API call. A successful exploit could allow the attacker to inject arbitrary code that would be executed on the underlying operating system of the affected device. To exploit this vulnerability, the attacker would need to have a privileged set of credentials to the 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 · moderate confidence

A vulnerability in the Cisco IOS XE Software web UI allows an authenticated attacker with privileged credentials to inject and execute arbitrary code with root privileges by tampering with a specific configuration file and sending a crafted API call. The root cause is improper sanitization of values parsed from that configuration file.

MitigationApply the Cisco vendor patch for CVE-2021-1443 when available. Until then, restrict access to the web UI to trusted users only, minimize the number of privileged accounts, and monitor for suspicious configuration changes.

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 XeOperating system
Affected:= 16.9.1= 16.9.1a= 16.9.1b= 16.9.1c= 16.9.1d= 16.9.1s= 16.9.2= 16.9.2a= 16.9.2s= 16.9.3= 16.9.3a= 16.9.3h

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

CVSS:3.1/AV:N/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 installed IOS XE version
    Run 'show version' or 'show version | include IOS XE' on the device CLI
    Affected if The version matches 16.9.1, 16.9.1a, 16.9.1b, 16.9.1c, 16.9.1d, 16.9.1s, 16.9.2, 16.9.2a, 16.9.2s, 16.9.3, 16.9.3a, or 16.9.3h
  2. Confirm web UI is enabled
    Run 'show http server' or check the configuration for 'ip http server' or 'ip http secure-server'
    Affected if HTTP or HTTPS server is enabled and accessible
  3. Audit privileged user accounts
    Run 'show users' and review 'show running-config | include username' to identify all accounts with privilege level 15
    Affected if Multiple privileged accounts exist beyond those expected, or unknown accounts are present
  4. Check for suspicious configuration changes
    Run 'show archive config differences' or review configuration change logs if logging is enabled
    Affected if Unexpected modifications to the configuration appear, particularly to files parsed by the web UI
  5. Inspect for signs of code execution
    Look for unexpected files in the filesystem with 'dir flash:' and check for unfamiliar processes or cron jobs
    Affected if New or unknown files appear on the device, or unexpected processes are running

The device is affected if it runs an affected IOS XE version (16.9.1 through 16.9.3h) AND has the web UI enabled AND an attacker with privileged credentials could access it.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Cisco vendor patch for CVE-2021-1443 when available. Until then, restrict access to the web UI to trusted users only, minimize the number of privileged accounts, and monitor for suspicious configuration changes.

Fix this in Ios Xe Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,480
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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-2021-1443 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