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Nextscale N1200 Enclosure FirmwareOperating system · Lenovo

CVE-2021-3849

CRITICAL · 9.8 CVSS v3.1 Published 2022-04-22
Fix available
A fix is available. Upgrade to 44a-3.70 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
An authentication bypass vulnerability was discovered in the web interface of the Lenovo Fan Power Controller2 (FPC2) and Lenovo System Management Module (SMM) firmware that could allow an unauthenticated attacker to execute commands on the SMM and FPC2. SMM2 is not affected.

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 authentication bypass vulnerability exists in the web interface of Lenovo Fan Power Controller2 (FPC2) and System Management Module (SMM) firmware, allowing unauthenticated attackers to execute arbitrary commands on affected devices. SMM2 is confirmed not vulnerable.

MitigationApply firmware updates provided by Lenovo for FPC2 and SMM devices; until patched, restrict network access to management interfaces and monitor for unauthorized access attempts.

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
Nextscale N1200 Enclosure FirmwareOperating system
Affected:< fhet50b-2.90
Thinkagile Hx Enclosure Certified Node FirmwareOperating system
Affected:< tesm28b-1.21
Thinkagile Vx Enclosure FirmwareOperating system
Affected:< tesm28b-1.21
Thinksystem D2 Enclosure FirmwareOperating system
Affected:< tesm28b-1.21
Nextscale Fan Power Controller FirmwareOperating system
Affected:< 44a-3.70

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 the device model
    Determine if the device is a Fan Power Controller2 (FPC2) or System Management Module (SMM). Note that SMM2 devices are not affected by this vulnerability.
    Affected if The device is FPC2 or SMM (not SMM2) and the model matches one of the affected product lines.
  2. Check the installed firmware version
    Access the device management interface or use the appropriate CLI command to retrieve the current firmware version. Compare against the affected version ranges: N1200 < fhet50b-2.90, Thinkagile Hx/Vx and Thinksystem D2 < tesm28b-1.21, IBM Nextscale FPC < 44a-3.70.
    Affected if The installed firmware version is lower than the specified threshold for your device model.
  3. Verify web interface status
    Check if the web-based management interface is enabled and accessible on the device. This is the attack vector for the authentication bypass.
    Affected if The web interface is enabled and exposed on the network.
  4. Assess network exposure
    Determine if the management web interface is reachable from network segments that are not strictly controlled. Check for exposure to untrusted networks.
    Affected if The management interface is accessible from untrusted network segments or the internet.

You are affected if your device is an FPC2 or SMM (not SMM2) model running firmware versions below the thresholds listed, and the web management interface is enabled and accessible.

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 44a-3.70 or later
Fixed in 44a-3.70
Interim mitigation

Apply firmware updates provided by Lenovo for FPC2 and SMM devices; until patched, restrict network access to management interfaces and monitor for unauthorized access attempts.

Recommended fix High confidence

fhet50b-2.90 (Nextscale N1200), tesm28b-1.21 (Thinkagile Hx/Vx, Thinksystem D2), 44a-3.70 (Nextscale Fan Power Controller)

  1. 1. Identify the current firmware version of the affected enclosure or Fan Power Controller by accessing the web interface or using Lenovo's management tools (e.g., XCC, IMM, or LXCA).
  2. 2. Navigate to the Lenovo support website (support.lenovo.com) and locate the firmware download page for your specific product model.
  3. 3. Download the fixed firmware version: fhet50b-2.90 for Nextscale N1200, tesm28b-1.21 for Thinkagile Hx/Vx and Thinksystem D2, or 44a-3.70 for Nextscale Fan Power Controller.
  4. 4. Review Lenovo's firmware update documentation and ensure the system is properly powered and stable before initiating the update.
  5. 5. Upload and apply the firmware update through the management interface (web UI or command-line tools), following Lenovo's recommended procedures.
  6. 6. After the update completes, verify the new firmware version is installed and confirm the web interface authentication is functioning correctly.
  7. 7. Test that unauthenticated access is no longer possible by attempting to access the web interface without credentials.
Caveat Firmware updates on BMC/management modules carry inherent risk; ensure proper power backup and follow Lenovo's update procedure to avoid leaving the device in an unusable state.

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

Fix this in Nextscale N1200 Enclosure Firmware 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-2021-3849 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