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Idrac9 FirmwareOperating system · Dell

CVE-2021-21538

CRITICAL · 10.0 CVSS v3.1 Published 2021-07-29
Fix available
A fix is available. Upgrade to 4.40.10.00 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

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
Dell EMC iDRAC9 versions 4.40.00.00 and later, but prior to 4.40.10.00, contain an improper authentication vulnerability. A remote unauthenticated attacker could potentially exploit this vulnerability to gain access to the virtual console.

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

Dell EMC iDRAC9 versions 4.40.00.00 through 4.40.09.00 contain an improper authentication vulnerability that allows remote unauthenticated attackers to bypass authentication and gain access to the virtual console (KVM) functionality of the server's out-of-band management interface.

MitigationUpdate iDRAC9 firmware to version 4.40.10.00 or later to remediate this authentication bypass vulnerability. Test the update in a staging environment before applying to production, as iDRAC is a critical infrastructure component.

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
Idrac9 FirmwareOperating system
Affected:>= 4.40.00.00, < 4.40.10.00

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
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 iDRAC9 firmware version
    Access the iDRAC web interface and navigate to iDRAC Settings > Overview > General > iDRAC Info, or use the racadm command: racadm get idrac.webserver.1.url or racadm getversion
    Affected if Version falls within 4.40.00.00 through 4.40.09.00
  2. Confirm remote management is enabled
    Check if iDRAC network access is enabled via web UI (iDRAC Settings > Services > Web Server) or via racadm: racadm get idrac.webserver.1.enabled
    Affected if Remote management interface is accessible over the network
  3. Verify KVM/virtual console status
    Check if virtual console is enabled via web UI (iDRAC Settings > Services > Virtual Console) or via racadm: racadm get iDRAC.VirtualConsole.1.Enabled
    Affected if KVM or virtual console functionality is turned on
  4. Check for exposed iDRAC interface
    Scan network for open ports on the iDRAC management interface (ports 443, 623 UDP for IPMI) or review firewall rules to confirm the iDRAC web interface is reachable from untrusted networks
    Affected if iDRAC management interface is exposed to untrusted networks or the internet

The environment is affected if iDRAC9 firmware version is 4.40.00.00 or higher but below 4.40.10.00, and the KVM/virtual console feature is enabled and reachable from a network where untrusted attackers could attempt authentication bypass.

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 4.40.10.00 or later
Fixed in 4.40.10.00
Vendor patch www.dell.com →
Interim mitigation

Update iDRAC9 firmware to version 4.40.10.00 or later to remediate this authentication bypass vulnerability. Test the update in a staging environment before applying to production, as iDRAC is a critical infrastructure component.

Recommended fix High confidence

iDRAC9 firmware version 4.40.10.00 or later

  1. Backup the current iDRAC configuration settings before performing the firmware update
  2. Access the iDRAC web interface or use the iDRAC Lifecycle Controller
  3. Download the iDRAC9 firmware version 4.40.10.00 or later from the Dell support portal at https://www.dell.com/support/kbdoc/000186420
  4. Upload the firmware update file through the iDRAC web interface under "Maintenance" > "System Update" > "Firmware Update"
  5. Follow the on-screen prompts to apply the firmware update, ensuring stable power to the server during the process
  6. Allow the iDRAC to reboot and complete the update process
  7. Verify the firmware version has been updated to 4.40.10.00 or later by checking the iDRAC web interface under "Maintenance" > "System Update" > "Firmware Inventory"
  8. Restore the iDRAC configuration from the backup taken in step 1
Caveat Firmware update may cause brief service interruption; ensure stable power and plan maintenance window

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

Fix this in Idrac9 Firmware Scoped from the published advisory
  • Consultation6.0 h
  • Implementation10.0 h
  • Testing6.0 h
  • Review / QA3.0 h
25.0 hours of engineering $4,440
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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-2021-21538 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
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