# CVE-2021-32766: Nextcloud Text app can disclose existence of folders in "File Drop" link share

> Attackers with valid File Drop links can enumerate folder existence in Nextcloud Text shares, leaking directory structure information.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 7 Sep 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-gcf3-3wmc-88jr

## What is CVE-2021-32766?

CVE-2021-32766 is a medium-severity vulnerability in Nextcloud Nextcloud Server, published on 7 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Nextcloud Text is an open source plaintext editing application which ships with the nextcloud server. In affected versions the Nextcloud Text application returned different error messages depending on whether a folder existed in a public link share. This is problematic in case the public link share has been created with "Upload Only" privileges. (aka "File Drop"). A link share recipient is not expected to see which folders or files exist in a "File Drop" share. Using this vulnerability an attacker is able to enumerate folders in such a share. Exploitation requires that the attacker has access to a valid affected "File Drop" link share. It is recommended that the Nextcloud Server is upgraded to 20.0.12, 21.0.4 or 22.0.1. Users who are unable to upgrade are advised to disable the Nextcloud Text application in the app settings.

Weakness: CWE-209 (Generation of Error Message Containing Sensitive Information)

## Which versions are affected by CVE-2021-32766?

It affects 1 product.


Products: Nextcloud Nextcloud Server.

## How do I fix CVE-2021-32766?

Upgrade to a fixed version.

## Is CVE-2021-32766 being exploited?

There is no known exploitation of CVE-2021-32766 in the wild and no public exploit code.

## Other vulnerabilities in Nextcloud Nextcloud Server

- [CVE-2021-32802](https://insights.sbomify.com/CVE-2021-32802/): Preview generation used third-party library not suited for user-generated content in Nextcloud server (critical 9.3)
- [CVE-2023-26482](https://insights.sbomify.com/CVE-2023-26482/): Scope of workflow operations is not validated in nextcloud server (critical 9.1)
- [CVE-2018-3775](https://insights.sbomify.com/CVE-2018-3775/): Auth bypass in Nextcloud Server (high 8.8)
- [CVE-2023-35172](https://insights.sbomify.com/CVE-2023-35172/): Nextcloud Server password reset endpoint is not brute force protected (high 8.7)
- [CVE-2023-32320](https://insights.sbomify.com/CVE-2023-32320/): Nextcloud Server's brute force protection allows someone to send more requests than intended (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-32766 and fix it if it is affected.

What it is: CVE-2021-32766 is a medium-severity vulnerability in Nextcloud Nextcloud Server, published on 7 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-32766 in the wild and no public exploit code.

Affected product: Nextcloud Nextcloud Server. 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-2021-32766/ (Markdown: https://insights.sbomify.com/CVE-2021-32766/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32766
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32766
- OSV: https://osv.dev/vulnerability/CVE-2021-32766

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32766/
Summaries are generated and may contain mistakes; the official description above is the record.