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Couchbase ServerApplication · Couchbase

CVE-2021-35943

CRITICAL · 9.8 CVSS v3.1 Published 2021-09-29
Fix available
A fix is available. Upgrade to 6.6.3 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
Couchbase Server 6.5.x and 6.6.x through 6.6.2 has Incorrect Access Control. Externally managed users are not prevented from using an empty password, per RFC4513.

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

Couchbase Server 6.5.x through 6.6.2 contains an incorrect access control vulnerability where externally managed users (such as LDAP/Active Directory users) are not prevented from authenticating with empty passwords, contrary to RFC4513 authentication requirements. This allows unauthorized access to the database without proper credential validation.

MitigationUpgrade Couchbase Server to a version that addresses this vulnerability and enforce password complexity policies for externally managed users. Additionally, configure the authentication backend to reject empty passwords according to RFC4513.

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
Couchbase ServerApplication
Affected:>= 6.5.0, <= 6.5.2>= 6.6.0, < 6.6.3

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 installed Couchbase Server version
    Use the Couchbase CLI tool (couchbase-cli) or check the product UI to retrieve the exact version number of the installed Couchbase Server
    Affected if The version falls within 6.5.0 to 6.5.2 or 6.6.0 to 6.6.2
  2. Determine if external authentication is enabled
    Check the Couchbase Server authentication settings to see if LDAP or Active Directory integration is configured as an external authentication source
    Affected if External user authentication (LDAP/AD) is enabled and in use
  3. Verify authentication configuration for empty passwords
    Inspect the Couchbase Server authentication configuration files or settings to determine whether the system allows authentication with empty passwords for externally managed users
    Affected if The configuration permits empty password authentication for externally managed users

Your environment is affected if Couchbase Server version is 6.5.0-6.5.2 or 6.6.0-6.6.2 AND external LDAP/AD authentication is enabled AND empty password authentication is permitted for those external 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 6.6.3 or later
Fixed in 6.6.3
Interim mitigation

Upgrade Couchbase Server to a version that addresses this vulnerability and enforce password complexity policies for externally managed users. Additionally, configure the authentication backend to reject empty passwords according to RFC4513.

Recommended fix Moderate confidence

Couchbase Server 6.6.3 or later (for 6.6.x users); Couchbase Server 6.5.3 or later if available (for 6.5.x users)

  1. 1. Back up your Couchbase Server configuration and data before upgrading.
  2. 2. Download Couchbase Server version 6.6.3 or later from the official Couchbase downloads page (www.couchbase.com/downloads).
  3. 3. Plan your upgrade approach: for production environments, use the rolling upgrade procedure or offline upgrade as appropriate for your cluster configuration.
  4. 4. For clusters with external authentication (LDAP/Active Directory), verify that empty passwords are no longer accepted after the upgrade by testing user authentication.
  5. 5. After upgrade, confirm that externally managed users must provide a valid non-empty password per RFC4513 requirements.
  6. 6. Review user authentication logs to ensure the vulnerability is remediated.
Caveat Review Couchbase Server release notes for any breaking changes between your current version and 6.6.3; test upgrades in a non-production environment first

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

Fix this in Couchbase Server Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing10.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,580
Get the upgrade done

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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-2021-35943 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