# CVE-2025-66510: Nextcloud Server Contacts Search allowed users to retrieve contact information of other users beyond their contact list

> Authenticated users can retrieve personal data of other users beyond their contact list due to missing access controls in the contacts search feature.

- **Severity:** Medium 4.5 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/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:** 5 Dec 2025
- **Also known as:** BIT-nextcloud-2025-66510, GHSA-495w-cqv6-wr59

## What is CVE-2025-66510?

CVE-2025-66510 is a medium-severity vulnerability in Nextcloud Nextcloud Server, 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 Server is a self hosted personal cloud system. In Nextcloud Server prior to 31.0.10 and 32.0.1 and Nextcloud Enterprise Server prior to 28.0.14.11, 29.0.16.8, 30.0.17.3, and 31.0.10, contacts search allowed to retrieve personal data of other users (emails, names, identifiers) without proper access control. This allows an authenticated user to retrieve information about accounts that are not related or added as contacts.

Weakness: CWE-359 (Exposure of Private Personal Information to an Unauthorized Actor)

## Which versions are affected by CVE-2025-66510?

1 open source package ship an affected version, including nextcloud. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `nextcloud` | Bitnami | From 31.0.0 | 31.0.10, 32.0.1 |

Products: Nextcloud Nextcloud Server.

## How do I fix CVE-2025-66510?

Upgrade nextcloud to a fixed version for your release line: 31.0.10 or 32.0.1.

## Is CVE-2025-66510 being exploited?

There is no known exploitation of CVE-2025-66510 in the wild and no public exploit code.

## 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-2025-66510 and fix it if it is affected.

What it is: CVE-2025-66510 is a medium-severity vulnerability in Nextcloud Nextcloud Server, 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-2025-66510 in the wild and no public exploit code.

Affected packages and fixed versions:
- nextcloud (Bitnami): affected from 31.0.0; fixed in 31.0.10, 32.0.1

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-2025-66510/ (Markdown: https://insights.sbomify.com/CVE-2025-66510/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-66510
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-66510
- OSV: https://osv.dev/vulnerability/CVE-2025-66510

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-66510/
Summaries are generated and may contain mistakes; the official description above is the record.