# CVE-2021-32688: Application specific tokens can change their own scope

> Nextcloud Server application tokens could escalate privileges to access the filesystem due to missing permission checks, requiring an upgrade to fix.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 12 Jul 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-48m7-7r2r-838r

## What is CVE-2021-32688?

CVE-2021-32688 is a high-severity vulnerability in Fedoraproject Fedora, published on 12 Jul 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Nextcloud Server is a Nextcloud package that handles data storage. Nextcloud Server supports application specific tokens for authentication purposes. These tokens are supposed to be granted to a specific applications (e.g. DAV sync clients), and can also be configured by the user to not have any filesystem access. Due to a lacking permission check, the tokens were able to change their own permissions in versions prior to 19.0.13, 20.0.11, and 21.0.3. Thus fileystem limited tokens were able to grant themselves access to the filesystem. The issue is patched in versions 19.0.13, 20.0.11, and 21.0.3. There are no known workarounds aside from upgrading.

Weakness: CWE-552 (Files or Directories Accessible to External Parties), CWE-285 (Improper Authorization)

## Which versions are affected by CVE-2021-32688?

It affects 2 products.


Products: Fedoraproject Fedora, Nextcloud Nextcloud Server.

## How do I fix CVE-2021-32688?

Upgrade to a fixed version.

## Is CVE-2021-32688 being exploited?

There is no known exploitation of CVE-2021-32688 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-32688 and fix it if it is affected.

What it is: CVE-2021-32688 is a high-severity vulnerability in Fedoraproject Fedora, published on 12 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-2021-32688 in the wild and no public exploit code.

Affected product: Fedoraproject Fedora. 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-2021-32688/ (Markdown: https://insights.sbomify.com/CVE-2021-32688/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32688
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32688
- OSV: https://osv.dev/vulnerability/CVE-2021-32688

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32688/
Summaries are generated and may contain mistakes; the official description above is the record.