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Fabric Operating SystemOperating system · Broadcom

CVE-2021-27789

MEDIUM · 6.5 CVSS v3.1 Published 2022-03-18
Fix available
A fix is available. Upgrade to 8.2.3a / 9.0.1a 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
The Web application of Brocade Fabric OS before versions Brocade Fabric OS v9.0.1a and v8.2.3a contains debug statements that expose sensitive information to the program's standard output device. An attacker who has compromised the FOS system may utilize this weakness to capture sensitive information, such as user credentials.

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

The Web application component of Brocade Fabric OS contains debug statements that output sensitive information, including user credentials, to the standard output device. An attacker who has already compromised the FOS system can exploit this weakness to capture credentials exposed through these debug statements. The vulnerability affects versions prior to v9.0.1a and v8.2.3a.

MitigationUpgrade Brocade Fabric OS to version v9.0.1a, v8.2.3a, or later to remove the debug statements that expose sensitive information. Since this is a post-compromise vulnerability, also ensure the initial compromise vector is identified and remediated.

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:< 8.2.3a>= 9.0.0, < 9.0.1a

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. Identify the Fabric OS version
    Run the command 'version' or 'fosadmin --version' on the FOS device to obtain the installed version string.
    Affected if The version is below 8.2.3a, or is 9.0.0 or higher but below 9.0.1a.
  2. Verify the web application component is active
    Check if the web management interface is enabled by running 'webd --status' or inspecting the running services with 'ps | grep web' to confirm the web component is running.
    Affected if The web application component is enabled and running on the device.
  3. Examine system logs for credential exposure
    Review log files in /var/log/ or output from 'dmesg' for debug statements that may contain plain-text user credentials or session tokens.
    Affected if Debug output containing username/password strings or API keys is visible in system logs or standard output.
  4. Check for unauthorized access indicators
    Since this is a post-compromise vulnerability, review authentication logs for suspicious sessions, especially from internal IP addresses or unexpected users, using 'authLog' or equivalent log inspection.
    Affected if Evidence exists of an attacker who has already compromised the FOS system and may be capturing debug output.

You are affected if your Fabric OS version is below 8.2.3a or between 9.0.0 and 9.0.1a, and an attacker has already gained access to capture credentials from debug statements in the web application component.

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 8.2.3a / 9.0.1a or later
Fixed in 8.2.3a9.0.1a
Interim mitigation

Upgrade Brocade Fabric OS to version v9.0.1a, v8.2.3a, or later to remove the debug statements that expose sensitive information. Since this is a post-compromise vulnerability, also ensure the initial compromise vector is identified and remediated.

Recommended fix High confidence

Brocade Fabric OS v8.2.3a or v9.0.1a and later

  1. 1. Determine current Fabric OS version using 'version' command or Fabric Web GUI
  2. 2. If running version 8.x < 8.2.3a, schedule maintenance window and upgrade to v8.2.3a or later
  3. 3. If running version 9.0.0, upgrade to v9.0.1a or later
  4. 4. After upgrade, verify the version change using 'version' command
  5. 5. As a precaution due to exposed credentials, reset passwords for all user accounts, especially administrative accounts

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

Fix this in Fabric Operating System 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-2021-27789 in production — separate from our analysis above.

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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