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Cohesity DataplatformApplication · Cohesity

CVE-2021-28123

CRITICAL · 9.8 CVSS v3.1 Published 2021-04-02
Fix available
A fix is available. Upgrade to 6.3.1g / 6.4.1c or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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
Undocumented Default Cryptographic Key Vulnerability in Cohesity DataPlatform version 6.3 prior 6.3.1g, 6.4 up to 6.4.1c and 6.5.1 through 6.5.1b. The ssh key can provide an attacker access to the linux system in the affected version.

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

An undocumented default SSH cryptographic key was discovered in Cohesity DataPlatform versions 6.3 prior to 6.3.1g, 6.4 up to 6.4.1c, and 6.5.1 through 6.5.1b. This hardcoded SSH key provides remote unauthenticated attackers with direct access to the underlying Linux system, bypassing all authentication controls.

MitigationReplace the undocumented/default SSH key with a unique, properly managed cryptographic key on all affected Cohesity DataPlatform installations, and rotate credentials immediately.

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
Cohesity DataplatformApplication
Affected:>= 6.3, < 6.3.1g>= 6.4, < 6.4.1c>= 6.5.1, < 6.5.1b

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

CVSS:3.1/AV:N/AC:L/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 checks

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

  1. Identify Cohesity DataPlatform version
    Run 'cohesity version' or access the UI dashboard to view the installed DataPlatform version number
    Affected if The installed version is 6.3.x (before 6.3.1g), 6.4.x (before 6.4.1c), or 6.5.1.x (before 6.5.1b)
  2. Confirm SSH service is enabled
    Check if SSH (port 22) is listening and accessible on the Cohesity node by running 'netstat -tlnp | grep :22' or scanning the IP from an external host
    Affected if SSH service is running and exposed (even to internal networks)
  3. Verify SSH key-based authentication configuration
    Examine /root/.ssh/authorized_keys or the directory containing SSH authorized keys for any undocumented or default keys, particularly looking for hardcoded RSA/ED25519 keys not generated during your setup
    Affected if An undocumented/default SSH key exists in authorized_keys that was not intentionally provisioned by your administration team

You are affected if your Cohesity DataPlatform version falls within 6.3 to <6.3.1g, 6.4 to <6.4.1c, or 6.5.1 to <6.5.1b AND SSH is accessible with a hardcoded key present.

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 6.3.1g / 6.4.1c / 6.5.1b or later
Fixed in 6.3.1g6.4.1c6.5.1b
Interim mitigation

Replace the undocumented/default SSH key with a unique, properly managed cryptographic key on all affected Cohesity DataPlatform installations, and rotate credentials immediately.

Recommended fix High confidence

6.3.1g (or later 6.3.x), 6.4.1c (or later 6.4.x), or 6.5.1b (or later 6.5.1.x)

  1. Identify current Cohesity DataPlatform version using 'cohesity --version' or web UI
  2. Review the upgrade path: if on 6.3.x, upgrade to 6.3.1g or later; if on 6.4.x, upgrade to 6.4.1c or later; if on 6.5.1.x, upgrade to 6.5.1b or later
  3. Follow Cohesity upgrade documentation: ensure adequate backup of cluster configuration
  4. Download the upgrade package from Cohesity support portal (support.cohesity.com)
  5. Execute upgrade via UI (Cluster > Settings > Software Upgrade) or CLI: 'cohesity-upgrade --start --package <package_file>'
  6. After upgrade, verify version with 'cohesity --version'
  7. As a security best practice after patching, rotate all SSH keys and ensure no undocumented/default keys remain on the system
  8. Monitor Cohesity security advisories for future updates
Caveat Standard Cohesity upgrade considerations apply: ensure cluster health is green before upgrade, and test in non-production environment first

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

Fix this in Cohesity Dataplatform Scoped from the published advisory
  • Consultation8.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,380
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,608.

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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-2021-28123 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