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Metamako Operating SystemOperating system · Arista

CVE-2021-28497

HIGH · 7.8 CVSS v3.1 Published 2021-09-09
Fix available
A fix is available. Upgrade to 0.32.0 or later.
See remediation →
80/100
Remediation priority · High
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
In Arista's MOS (Metamako Operating System) software which is supported on the 7130 product line, under certain conditions, the bash shell might be accessible to unprivileged users in situations where they should not have access. This issue affects: Arista Metamako Operating System All releases in the MOS-0.1x train MOS-0.26.6 and below releases in the MOS-0.2x train MOS-0.31.1 and below releases in the MOS-0.3x train

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

Arista MOS (Metamako Operating System) on the 7130 product line contains a privilege escalation vulnerability where unprivileged users can gain access to the bash shell under certain conditions where shell access should be restricted.

MitigationApply vendor-supplied patches by updating to MOS-0.26.7 or higher for the 0.2x train, MOS-0.31.2 or higher for the 0.3x train, or a patched version for the 0.1x train. Contact Arista Networks for specific patch availability.

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
Metamako Operating SystemOperating system
Affected:<= 0.26.6>= 0.31.0, < 0.32.0

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

CVSS:3.1/AV:L/AC:L/PR:L/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. Determine the installed MOS version
    Run 'show version' or check the system information on the Arista 7130 device running MOS. The output will display the MOS version number.
    Affected if The installed version is 0.26.6 or lower, OR between 0.31.0 and 0.31.1 inclusive (any version < 0.32.0 from the 0.31.x train)
  2. Confirm this is a 7130 series device
    Run 'show hardware' or check the device model number. This vulnerability specifically affects the 7130 product line.
    Affected if The device is an Arista 7130 series running the affected MOS versions listed above
  3. Verify shell access restrictions
    Check if unprivileged users have access to shell features that should be restricted. Review user role configurations and any exposed shell access points.
    Affected if Unprivileged or non-admin users can access bash shell or shell escape functions that should be blocked

You are affected if your Arista 7130 device runs MOS version 0.26.6 or lower, or any version from 0.31.0 up to (but not including) 0.32.0, and unprivileged users can somehow reach the bash shell.

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.

dbcve · scoped
Upgrade available Upgrade to 0.32.0 or later
Fixed in 0.32.0
Interim mitigation

Apply vendor-supplied patches by updating to MOS-0.26.7 or higher for the 0.2x train, MOS-0.31.2 or higher for the 0.3x train, or a patched version for the 0.1x train. Contact Arista Networks for specific patch availability.

Recommended fix Moderate confidence

MOS version 0.32.0 or later in the MOS-0.3x train (or latest stable MOS release)

  1. 1. Identify the current MOS version running on the 7130 device using 'show version' or 'mosh --version'
  2. 2. Schedule a maintenance window for the upgrade (this may require network downtime)
  3. 3. Download the fixed MOS release (version 0.32.0 or later from the MOS-0.3x train, or a later stable release) from the Arista portal at https://www.arista.com/en/support/software-download
  4. 4. Upload the new MOS image to the device's storage using SCP, FTP, or the device's web interface
  5. 5. Verify the image integrity using the provided MD5/SHA256 checksum
  6. 6. Execute the upgrade command: 'software install <image-file>' or use the appropriate MOS upgrade procedure
  7. 7. Confirm the upgrade completes successfully and the device reboots
  8. 8. After reboot, verify the new version is running: 'show version'
Caveat Check Arista release notes for any configuration or feature changes between your current version and the target version before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Metamako Operating System Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,570
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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-2021-28497 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