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Fabric Operating SystemOperating system · Broadcom

CVE-2021-27796

MEDIUM · 6.5 CVSS v3.1 Published 2022-02-21
Fix available
A fix is available. Upgrade to 7.4.1d / 8.0.1b or later.
See remediation →
71/100
Remediation priority · Elevated
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 Brocade Fabric OS versions before Brocade Fabric OS v8.0.1b, v7.4.1d could allow an authenticated attacker within the restricted shell environment (rbash) as either the “user” or “factory” account, to read the contents of any file on the filesystem utilizing one of a few available binaries.

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

Brocade Fabric OS versions before v8.0.1b and v7.4.1d contain a file read vulnerability. Authenticated attackers with limited 'user' or 'factory' accounts operating within the restricted bash (rbash) environment can exploit certain binaries to read arbitrary files on the filesystem, enabling information disclosure beyond their intended permissions.

MitigationUpgrade Brocade Fabric OS to v8.0.1b, v7.4.1d or later. Until the patch is applied, minimize exposure by restricting network access to management interfaces and monitoring for unauthorized access attempts using the affected accounts.

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
Fabric Operating SystemOperating system
Affected:< 7.4.1d>= 8.0.0, < 8.0.1b

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

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

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 Fabric OS version
    Log into the Fabric OS management interface (via CLI or web GUI) and run the command to display the system version, typically 'version' or 'firmwareshow'
    Affected if The displayed version is earlier than 7.4.1d, or is 8.0.0 or 8.0.1a (versions < 7.4.1d or >= 8.0.0 and < 8.0.1b)
  2. Identify configured user accounts
    Use the 'userconfigshow' or 'userconfig' command to list all user accounts defined on the device
    Affected if Any account with 'user' or 'factory' role is present on the system (these are the limited privilege accounts that can exploit the flaw)
  3. Verify rbash environment for limited accounts
    Check the shell environment assigned to user/factory accounts using 'usershow' or similar command to confirm they operate within restricted bash (rbash)
    Affected if The affected accounts are configured to use the default restricted shell environment (this is the default for these account types)
  4. Assess network exposure of management interface
    Review firewall rules or access control lists protecting the Fabric OS management ports (TCP 22 for SSH, TCP 80/443 for web UI)
    Affected if Management interfaces are accessible from untrusted networks where unauthorized individuals could obtain valid user/factory credentials

You are affected if your Fabric OS version falls in the range < 7.4.1d or >= 8.0.0 and < 8.0.1b AND you have user or factory accounts configured on the system.

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 7.4.1d / 8.0.1b or later
Fixed in 7.4.1d8.0.1b
Interim mitigation

Upgrade Brocade Fabric OS to v8.0.1b, v7.4.1d or later. Until the patch is applied, minimize exposure by restricting network access to management interfaces and monitoring for unauthorized access attempts using the affected accounts.

Recommended fix High confidence

Fabric OS 7.4.1d (or newer 7.x) / 8.0.1b (or newer 8.x)

  1. 1. Identify the current Fabric OS version using 'version' or 'firmwareShow' command
  2. 2. Download the appropriate fixed version from Broadcom support portal: version 7.4.1d or higher for 7.x branch, or version 8.0.1b or higher for 8.x branch
  3. 3. Review Broadcom upgrade documentation and release notes for the target version
  4. 4. Perform a backup of the current Fabric OS configuration
  5. 5. Upload the firmware using 'firmwareDownload' command or Fabric OS web interface
  6. 6. Verify the upgrade completed successfully and the new version is running
  7. 7. Confirm the vulnerability is resolved by verifying the fixed binaries no longer permit arbitrary file reads
Caveat Review release notes for compatibility with connected devices and any configuration changes required; ensure backup before upgrading

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

Fix this in Fabric Operating System Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,380
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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-2021-27796 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