# CVE-2021-37628: File Drop can be bypassed using Richdocuments app in nextcloud

> Attackers can bypass File Drop restrictions in Nextcloud public shares to read arbitrary files via the Richdocuments app.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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:** No
- **Published:** 7 Sep 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-pxhh-954f-8w7w

## What is CVE-2021-37628?

CVE-2021-37628 is a high-severity missing authorization vulnerability in nextcloud security-advisories, 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 Richdocuments is an open source collaborative office suite. In affected versions the File Drop features ("Upload Only" public link shares in Nextcloud) can be bypassed using the Nextcloud Richdocuments app. An attacker was able to read arbitrary files in such a share. It is recommended that the Nextcloud Richdocuments is upgraded to 3.8.4 or 4.2.1. If upgrading is not possible then it is recommended to disable the Richdocuments application.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2021-37628?

It affects 1 product.


Products: Nextcloud Richdocuments.

## How do I fix CVE-2021-37628?

No fix has been published for CVE-2021-37628 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-37628 being exploited?

There is no known exploitation of CVE-2021-37628 in the wild and no public exploit code.

## Other vulnerabilities in nextcloud security-advisories

- [CVE-2022-31024](https://insights.sbomify.com/CVE-2022-31024/): Federated editing allows iframing remote servers by default in richdocuments (medium 6.5)
- [CVE-2023-25150](https://insights.sbomify.com/CVE-2023-25150/): Document content of files can be obtained through Collabora for files of other users (medium 5.8)
- [CVE-2023-28645](https://insights.sbomify.com/CVE-2023-28645/): Secure view can be bypassed by using internal API endpoint in Nextcloud richdocuments (medium 5.7)
- [CVE-2021-37629](https://insights.sbomify.com/CVE-2021-37629/): Lack of ratelimit on Richdocuments OCS endpoint in nextcloud (medium 5.3)
- [CVE-2021-39223](https://insights.sbomify.com/CVE-2021-39223/): File path disclosure of shared files in Richdocuments application (medium 4.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-37628 and fix it if it is affected.

What it is: CVE-2021-37628 is a high-severity missing authorization vulnerability in nextcloud security-advisories, 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-2021-37628 in the wild and no public exploit code.

Affected product: nextcloud security-advisories. 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-2021-37628/ (Markdown: https://insights.sbomify.com/CVE-2021-37628/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-37628
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-37628
- OSV: https://osv.dev/vulnerability/CVE-2021-37628

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-37628/
Summaries are generated and may contain mistakes; the official description above is the record.