# CVE-2025-66549: Nextcloud Desktop discloses information when attempting to lock a file inside a end-to-end encrypted directory

> Nextcloud Desktop client leaks unencrypted file paths to the server when locking files in encrypted directories, exposing sensitive data to administrators.

- **Severity:** Low 2.4 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 5 Dec 2025
- **Updated:** 8 Dec 2025
- **Also known as:** DEBIAN-CVE-2025-66549, GHSA-h9xj-qh76-q3hw, UBUNTU-CVE-2025-66549

## What is CVE-2025-66549?

CVE-2025-66549 is a low-severity vulnerability in nextcloud security-advisories, published on 5 Dec 2025. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

Nextcloud Desktop is the desktop sync client for Nextcloud. Prior to 3.16.5, when trying to manually lock a file inside an end-to-end encrypted directory, the path of the file was sent to the server unencrypted, making it possible for administrators to see it in log files. This vulnerability is fixed in 3.16.5.

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

## Which versions are affected by CVE-2025-66549?

It affects 1 product.


Products: Nextcloud Desktop.

## How do I fix CVE-2025-66549?

Upgrade to a fixed version.

## Is CVE-2025-66549 being exploited?

There is no known exploitation of CVE-2025-66549 in the wild and no public exploit code.

## Other vulnerabilities in nextcloud security-advisories

- [CVE-2024-46958](https://insights.sbomify.com/CVE-2024-46958/): Misconfiguration in n/a (critical 9.1)
- [CVE-2020-8224](https://insights.sbomify.com/CVE-2020-8224/): Code injection in Desktop Client (high 7.8)
- [CVE-2020-8225](https://insights.sbomify.com/CVE-2020-8225/): Information disclosure in Desktop Client (high 7.5)
- [CVE-2021-37617](https://insights.sbomify.com/CVE-2021-37617/): Untrusted Search Path in Nextcloud Desktop Client (high 7.3)
- [CVE-2023-28999](https://insights.sbomify.com/CVE-2023-28999/): Nextcloud: Lack of authenticity of metadata keys allows a malicious server to gain access to E2EE folders (medium 6.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-66549 and fix it if it is affected.

What it is: CVE-2025-66549 is a low-severity vulnerability in nextcloud security-advisories, published on 5 Dec 2025. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2025-66549 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-2025-66549/ (Markdown: https://insights.sbomify.com/CVE-2025-66549/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-66549
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-66549
- OSV: https://osv.dev/vulnerability/CVE-2025-66549

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-66549/
Summaries are generated and may contain mistakes; the official description above is the record.