# CVE-2023-39962: Users can delete external storage mount points

> A malicious user can delete external storage mount points, causing data inaccessibility for all users.

- **Severity:** High 7.7 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/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:** No
- **Published:** 10 Aug 2023
- **Updated:** 3 Oct 2024
- **Also known as:** GHSA-xwxx-2752-w3xm

## What is CVE-2023-39962?

CVE-2023-39962 is a high-severity missing authorization vulnerability in Nextcloud Nextcloud Server, published on 10 Aug 2023. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 19.0.0 and prior to versions 19.0.13.10, 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.8, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1, a malicious user could delete any personal or global external storage, making them inaccessible for everyone else as well. Nextcloud server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 19.0.13.10, 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.9, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1 contain a patch for this issue. As a workaround, disable app files_external. This also makes the external storage inaccessible but retains the configurations until a patched version has been deployed.

Weakness: CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2023-39962?

It affects 1 product.


Products: Nextcloud Nextcloud Server.

## How do I fix CVE-2023-39962?

No fix has been published for CVE-2023-39962 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-39962 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-39962 exists.

## 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-2023-39962 and fix it if it is affected.

What it is: CVE-2023-39962 is a high-severity missing authorization vulnerability in Nextcloud Nextcloud Server, published on 10 Aug 2023. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-39962 exists.

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-2023-39962/ (Markdown: https://insights.sbomify.com/CVE-2023-39962/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-39962
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-39962
- OSV: https://osv.dev/vulnerability/CVE-2023-39962

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-39962/
Summaries are generated and may contain mistakes; the official description above is the record.