# CVE-2021-32748: WOPI API not protected by credentials/IP check

> Attackers can bypass document watermarks and download protections in Nextcloud Richdocuments due to missing WOPI API authentication checks.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/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:** 27 Jul 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-24x8-h6m2-9jf2

## What is CVE-2021-32748?

CVE-2021-32748 is a medium-severity missing authorization vulnerability in nextcloud security-advisories, published on 27 Jul 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Nextcloud Richdocuments in an open source self hosted online office. Nextcloud uses the WOPI ("Web Application Open Platform Interface") protocol to communicate with the Collabora Editor, the communication between these two services was not protected by a credentials or IP check. Whilst this does not result in gaining access to data that the user has not yet access to, it can result in a bypass of any enforced watermark on documents as described on the [Nextcloud Virtual Data Room](https://nextcloud.com/virtual-data-room/) website and [our documentation](https://portal.nextcloud.com/article/nextcloud-and-virtual-data-room-configuration-59.html). The Nextcloud Richdocuments releases 3.8.3 and 4.2.0 add an additional admin settings for an allowlist of IP addresses that can access the WOPI API. We recommend upgrading and configuring the allowlist to a list of Collabora servers. There is no known workaround. Note that this primarily results a bypass of any configured watermark or download protection using File Access Control. If you do not require or rely on these as a security feature no immediate action is required on your end.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2021-32748?

It affects 1 product.


Products: Nextcloud Richdocuments.

## How do I fix CVE-2021-32748?

No fix has been published for CVE-2021-32748 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-32748 being exploited?

There is no known exploitation of CVE-2021-32748 in the wild and no public exploit code.

## Other vulnerabilities in nextcloud security-advisories

- [CVE-2021-37628](https://insights.sbomify.com/CVE-2021-37628/): File Drop can be bypassed using Richdocuments app in nextcloud (high 7.5)
- [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)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-32748 and fix it if it is affected.

What it is: CVE-2021-32748 is a medium-severity missing authorization vulnerability in nextcloud security-advisories, published on 27 Jul 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-2021-32748 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-2021-32748/ (Markdown: https://insights.sbomify.com/CVE-2021-32748/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32748
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32748
- OSV: https://osv.dev/vulnerability/CVE-2021-32748

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32748/
Summaries are generated and may contain mistakes; the official description above is the record.