# CVE-2021-43963: Information disclosure in n/a

> Attackers with read access can extract bucket credentials from sync documents to gain write access, requiring shared bucket access and non-X.509 authentication.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Dec 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-v978-p5g5-3r76

## What is CVE-2021-43963?

CVE-2021-43963 is a high-severity vulnerability in n/a, published on 7 Dec 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

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.)

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2021-43963?

It affects 1 product.


Products: Couchbase Sync Gateway.

## How do I fix CVE-2021-43963?

No fix has been published for CVE-2021-43963 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-43963 being exploited?

There is no known exploitation of CVE-2021-43963 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2022-32563](https://insights.sbomify.com/CVE-2022-32563/): Couchbase Sync Gateway admin credentials not verified when using X.509 client cert authentication (critical 9.8)
- [CVE-2019-9039](https://insights.sbomify.com/CVE-2019-9039/): SQL Injection in Couchbase Sync Gateway (critical 9.8)
- [CVE-2025-52490](https://insights.sbomify.com/CVE-2025-52490/): Couchbase Sync Gateway shows cleartext passwords in redacted and unredacted output (high 7.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43963 and fix it if it is affected.

What it is: CVE-2021-43963 is a high-severity vulnerability in n/a, published on 7 Dec 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-43963 in the wild and no public exploit code.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-43963/ (Markdown: https://insights.sbomify.com/CVE-2021-43963/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43963
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43963
- OSV: https://osv.dev/vulnerability/CVE-2021-43963

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43963/
Summaries are generated and may contain mistakes; the official description above is the record.