Xclarity ControllerApplication · Lenovo

CVE-2021-3956

MEDIUM · 5.3 CVSS v3.1 Published 2022-05-18

Fix available

A fix is available. Upgrade to 1.51_tgbt24l / 2.32_psi342n or later.

See remediation →

62/100

Remediation priority · Elevated

Remotely reachable No privileges Zero-click

Official description

NVD · unedited

A read-only authentication bypass vulnerability was reported in the Third Quarter 2021 release of Lenovo XClarity Controller (XCC) firmware affecting XCC devices configured in LDAP Authentication Only Mode and using an LDAP server that supports “unauthenticated bind”, such as Microsoft Active Directory. An unauthenticated user can gain read-only access to XCC in such a configuration, thereby allowing the XCC device configuration to be viewed but not changed. XCC devices configured to use local authentication, LDAP Authentication + Authorization Mode, or LDAP servers that support only “authenticated bind” and/or “anonymous bind” are not affected.

Technical summary

dbcve analysis · high confidence

A read-only authentication bypass vulnerability in Lenovo XClarity Controller (XCC) firmware allows unauthenticated users to gain read-only access when the device is configured in LDAP Authentication Only Mode with an LDAP server supporting unauthenticated bind (such as Microsoft Active Directory). The attacker can view but not modify device configuration.

MitigationReconfigure affected XCC devices to use LDAP Authentication + Authorization Mode instead of Authentication Only Mode, or ensure the LDAP server is configured to require authenticated bind or anonymous bind rather than unauthenticated bind.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions

NVD · CPE data

Xclarity ControllerApplication

Affected:< 7.22_cdi382o< 2.32_psi342n< 3.41_tei382m< 4.83_tei3c0n< 1.51_tgbt24l

CVSS breakdown

From the vector

Attack vector: Network
Complexity: Low
Privileges: None
User interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: None

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

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Identify XCC firmware version

Access the XClarity Controller web interface and navigate to BMC Settings > Firmware Update, or use the command line: ipmitool -I lanplus -H <XCC_IP> -U <user> raw command to retrieve firmware version. Compare the displayed version string against the affected ranges: < 7.22_cdi382o, < 2.32_psi342n, < 3.41_tei382m, < 4.83_tei3c0n, < 1.51_tgbt24l.

Affected if The installed firmware version is lower than any of the listed version thresholds.
Confirm LDAP Authentication Only Mode is enabled

Log into XCC web UI, go to Security > Authentication, or use the XCC API endpoint /api/session to check the authentication configuration. Verify that the Authentication Mode is set to 'LDAP Authentication Only Mode' rather than 'LDAP Authentication + Authorization Mode'.

Affected if LDAP Authentication Only Mode is explicitly selected in the XCC authentication settings.
Verify LDAP server supports unauthenticated bind

Examine the LDAP server (typically Microsoft Active Directory) configuration. Check whether the LDAP directory is configured to allow anonymous bind or unauthenticated bind operations. This is typically done by reviewing AD domain policies or LDAP directory settings, or by attempting an unauthenticated bind query to the LDAP server.

Affected if The LDAP server accepts unauthenticated or anonymous bind requests without requiring user credentials.

A user is affected if their XCC firmware version is below any of the thresholds AND the device uses LDAP Authentication Only Mode AND the LDAP server permits unauthenticated bind.

Generated from the published advisory. Verify against your own configuration.

Remediation

dbcve · scoped

Upgrade available Upgrade to 1.51_tgbt24l / 2.32_psi342n / 3.41_tei382m or later

Fixed in 1.51_tgbt24l2.32_psi342n3.41_tei382m

Interim mitigation

Reconfigure affected XCC devices to use LDAP Authentication + Authorization Mode instead of Authentication Only Mode, or ensure the LDAP server is configured to require authenticated bind or anonymous bind rather than unauthenticated bind.

Recommended fix High confidence

XCC firmware version 7.22_cdi382o (or model-specific equivalents: 2.32_psi342n, 3.41_tei382m, 4.83_tei3c0n) or later

1. Identify the current XClarity Controller (XCC) firmware version by accessing the XCC web interface or using Lenovo XCC utility tools
2. Navigate to the Lenovo support website (support.lenovo.com) and locate the appropriate firmware download page for your XCC device
3. Download the fixed firmware version: 7.22_cdi382o or later (or the equivalent fixed release for your specific XCC model: 2.32_psi342n, 3.41_tei382m, or 4.83_tei3c0n)
4. Apply the firmware update through the XCC web interface (Firmware Update section) or using Lenovo XCC firmware update tools
5. After update completion, verify the new firmware version is installed
6. Alternatively (if upgrade not immediately possible), mitigate by changing LDAP configuration: switch from 'LDAP Authentication Only Mode' to 'LDAP Authentication + Authorization Mode', or configure LDAP server to disable 'unauthenticated bind', or use local authentication instead

Caveat Standard firmware update risks apply (ensure stable power during update); no major functional changes expected from security patch

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

Fix this in Xclarity Controller Scoped from the published advisory

Consultation3.0 h
Implementation6.0 h
Testing4.0 h
Review / QA2.0 h

15.0 hours of engineering $2,640

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References

Primary sources

support.lenovo.comVendor Advisory
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-3956 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2021-3956?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

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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

At a glance

A fix existsUpgrade to 1.51_tgbt24l / 2.32_psi342n or later

Severity 5.3 Medium

Exploit likelihood EPSS, next 30 days 0.8%

Affects: Xclarity Controller

Remediation

Need this fixed?

Fix this in Xclarity Controller 15 hrs · Low

Typical engagement from $2,640

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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.

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.

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.

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.

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.

Check your environment

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.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References