dbcve.org
Sync GatewayApplication · Couchbase

CVE-2021-43963

HIGH · 8.1 CVSS v3.1 Published 2021-12-07
Fix available
A fix is available. Upgrade to 2.8.3 or later.
See remediation →
87/100
Remediation priority · High
Remotely reachable 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 issue was discovered in Couchbase Sync Gateway 2.7.0 through 2.8.2. The bucket credentials used to read and write data in Couchbase Server were insecurely being stored in the metadata within sync documents written to the bucket. Users with read access could use these credentials to obtain write access. (This issue does not affect clusters where Sync Gateway is authenticated with X.509 client certificates. This issue also does not affect clusters where shared bucket access is not enabled on Sync Gateway.)

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

Couchbase Sync Gateway 2.7.0-2.8.2 insecurely stores bucket credentials (username/password) in plaintext within sync document metadata. Users with read access to these documents can extract the credentials and obtain write access to the Couchbase Server bucket.

MitigationUpgrade to a patched version of Sync Gateway, or enable X.509 client certificate authentication, or disable shared bucket access if not required.

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
Sync GatewayApplication
Affected:>= 2.7.0, < 2.8.3

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

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

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 Sync Gateway version
    Run 'curl http://localhost:4985/' or check the startup logs to identify the installed Sync Gateway version number
    Affected if Version is >= 2.7.0 and < 2.8.3 (including 2.8.0, 2.8.1, 2.8.2)
  2. Verify shared bucket access is enabled
    Inspect the Sync Gateway configuration file (sync_gateway.json) or REST API at /_node/{nodeid}/_config for the 'bucket_credentials' section under 'global' or within a database config
    Affected if Shared bucket access is configured with bucket credentials stored as username/password rather than X.509 certificates
  3. Examine sync document metadata for credentials
    Query the Sync Gateway REST API (GET /{db}/_all_docs) and inspect any _sync metadata objects within documents, looking for fields containing plaintext 'username' and 'password' values under bucket_credentials
    Affected if Sync documents contain plaintext bucket credentials in their _sync metadata
  4. Review user access to sync documents
    Check Sync Gateway user roles and channel assignments via GET /{db}/_user/{name} to determine which users have read access to documents that may contain bucket credentials
    Affected if Any user has read access to sync documents that could contain bucket credentials

You are affected if Sync Gateway version is 2.7.0 through 2.8.2 and shared bucket access with username/password authentication is enabled, allowing users with read access to extract plaintext credentials from sync document metadata.

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 2.8.3 or later
Fixed in 2.8.3
Interim mitigation

Upgrade to a patched version of Sync Gateway, or enable X.509 client certificate authentication, or disable shared bucket access if not required.

Recommended fix High confidence

Sync Gateway 2.8.3

  1. Upgrade Sync Gateway to version 2.8.3 or later
  2. After upgrading, verify that bucket credentials are no longer exposed in sync document metadata
  3. If immediate upgrade is not possible, ensure clusters are using X.509 client certificates for authentication (this mitigates the issue)
  4. Alternatively, ensure shared bucket access is disabled on Sync Gateway (this also mitigates the issue)

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

Fix this in Sync Gateway 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
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-2021-43963 in production — separate from our analysis above.

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What this is

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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
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