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Ios XeOperating system · Cisco

CVE-2020-3396

HIGH · 7.2 CVSS v3.1 Published 2020-09-24
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
74/100
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 file system on the pluggable USB 3.0 Solid State Drive (SSD) for Cisco IOS XE Software could allow an authenticated, physical attacker to remove the USB 3.0 SSD and modify sensitive areas of the file system, including the namespace container protections. The vulnerability occurs because the USB 3.0 SSD control data is not stored on the internal boot flash. An attacker could exploit this vulnerability by removing the USB 3.0 SSD, modifying or deleting files on the USB 3.0 SSD by using another device, and then reinserting the USB 3.0 SSD on the original device. A successful exploit could allow the attacker to remove container protections and perform file actions outside the namespace of the container with root 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

This vulnerability in Cisco IOS XE affects pluggable USB 3.0 SSDs where control data is not stored on internal boot flash. An attacker with physical access can remove the USB SSD, modify or delete files using another device, and reinsert it to bypass container protections and execute file operations outside the container namespace with root privileges.

MitigationApply Cisco-provided patches for CVE-2020-3396 to store USB 3.0 SSD control data on internal boot flash; implement physical security controls for devices with USB ports as an interim measure.

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:= 16.12.1

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
Physical
Complexity
Low
Privileges
High
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:P/AC:L/PR:H/UI:N/S:C/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. Check Cisco IOS XE version
    Run 'show version' or 'show version | include Version' to display the installed IOS XE software version
    Affected if Version equals 16.12.1 exactly (16.12.1 is the only affected version listed)
  2. Verify USB 3.0 SSD is connected
    Run 'show usb device' or 'show hardware inventory' to identify if a USB 3.0 SSD is physically attached to the device
    Affected if A USB 3.0 SSD is listed in the hardware inventory as an external storage device
  3. Check USB SSD control data storage location
    Run 'show running-config | include usb' or 'show usb' to examine the USB configuration and determine where control data is stored (internal boot flash vs external USB)
    Affected if Control data for the USB SSD is configured to be stored on the USB device itself rather than on internal boot flash
  4. Confirm container isolation configuration
    Run 'show container-info' or similar container status command to verify if container protections are active
    Affected if Containers are running and USB SSD is used for container storage without internal boot flash control data protection

A device is affected if it runs IOS XE version 16.12.1, has a USB 3.0 SSD attached, and the USB SSD control data is stored on the external USB rather than internal boot flash, allowing physical attackers to bypass container isolation.

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 Cisco-provided patches for CVE-2020-3396 to store USB 3.0 SSD control data on internal boot flash; implement physical security controls for devices with USB ports as an interim measure.

Fix this in Ios Xe 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
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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-2020-3396 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