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Fabric Operating SystemOperating system · Broadcom

CVE-2021-27790

HIGH · 7.8 CVSS v3.1 Published 2021-08-12
Fix available
A fix is available. Upgrade to 7.4.2h / 8.2.0_cbn4 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
The command ipfilter in Brocade Fabric OS before Brocade Fabric OS v.9.0.1a, v8.2.3, and v8.2.0_CBN4, and v7.4.2h uses unsafe string function to process user input. Authenticated attackers can abuse this vulnerability to exploit stack-based buffer overflows, allowing execution of arbitrary code as the root user account.

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 ipfilter command in Brocade Fabric OS uses unsafe string functions (likely strcpy/sprintf without bounds checking) to process user-supplied input. This creates a stack-based buffer overflow that authenticated attackers can exploit to achieve arbitrary code execution with root privileges.

MitigationUpgrade Brocade Fabric OS to v9.0.1a, v8.2.3, v7.4.2h or later to obtain the patched version. Restrict administrative access to trusted personnel as a compensating control until patching is possible.

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:< 7.4.2h>= 8.0.0, < 8.2.0_cbn4>= 8.2.1, < 8.2.3>= 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
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. Check Fabric OS version
    Run 'version' or 'firmwareShow' command on the Fabric OS device to retrieve the installed firmware version
    Affected if The version number falls into any of these ranges: < 7.4.2h, >= 8.0.0 and < 8.2.0_cbn4, >= 8.2.1 and < 8.2.3, or >= 9.0.0 and < 9.0.1a
  2. Identify ipfilter configuration
    Run 'ipfilter --show' or 'ipfilter -list' to display the current ipfilter rules and configuration
    Affected if The command executes successfully and returns ipfilter rules, indicating the feature is present and potentially exploitable
  3. Verify admin access controls
    Review user accounts with admin or root privileges using 'userconfig --show' or 'adminlist'
    Affected if Multiple non-targeted or shared admin accounts exist, increasing the attack surface for authenticated exploitation

The environment is affected if the Fabric OS version is within any of the vulnerable version ranges AND the ipfilter command is accessible to authenticated users.

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 7.4.2h / 8.2.0_cbn4 / 8.2.3 or later
Fixed in 7.4.2h8.2.0_cbn48.2.3
Interim mitigation

Upgrade Brocade Fabric OS to v9.0.1a, v8.2.3, v7.4.2h or later to obtain the patched version. Restrict administrative access to trusted personnel as a compensating control until patching is possible.

Recommended fix High confidence

7.4.2h (for 7.x branch), 8.2.0_CBN4 or 8.2.3 (for 8.x branch), or 9.0.1a (for 9.x branch)

  1. 1. Identify the current Fabric OS version by running 'version' or 'firmwareShow' command on the switch.
  2. 2. Determine which version branch you are on (7.x, 8.x, or 9.x) from the affected versions list.
  3. 3. For Fabric OS 7.x: Upgrade to version 7.4.2h or later.
  4. 4. For Fabric OS 8.x: If on 8.2.0_x branch, upgrade to 8.2.0_CBN4 or later; if on 8.2.1_x branch, upgrade to 8.2.3 or later.
  5. 5. For Fabric OS 9.x: Upgrade to version 9.0.1a or later.
  6. 6. Download the firmware from Broadcom support portal (support.broadcom.com) after authenticating.
  7. 7. Upload the firmware to the switch using 'firmwareDownload' command.
  8. 8. Verify the upgrade was successful with 'version' command confirming the fixed version is running.
Caveat Review Brocade Fabric OS release notes for any features deprecated or changed between your current version and the target fixed version; some legacy ipfilter configurations may need review

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
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2021-27790 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