# CVE-2025-66512: Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server and Server Enterprise prior to 31.0.12…

Source: https://junglewise.ai/threats/cve-2025-66512-nextcloud-server-is-a-self-hosted-personal-cloud-system-in  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-12-05  
License: CC BY 4.0 with a link back

CVE-2025-66512 · Severity: medium · CVSS 5.4 · Published 2025-12-05

Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server and Server Enterprise prior to 31.0.12 and 32.0.3, a missing sanitization allowed malicious users to circumvent the content security policy when a malicious user manages to trick a user it viewing an uploaded SVG outside of the Nextcloud Servers web page.

Technologies: [Nextcloud Server](https://junglewise.ai/threats/technologies/nextcloud-server). Vendors: [Nextcloud](https://junglewise.ai/threats/vendors/nextcloud).

## Quick answers

**Is CVE-2025-66512 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-66512 being exploited in the wild.

**How severe is CVE-2025-66512?** Medium severity, with a CVSS score of 5.4, published 5 December 2025.

**Which products and versions are affected?** Nextcloud Server. The advisory does not name versions.

**Is there a fix for CVE-2025-66512?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**Am I affected by CVE-2025-66512?** Check whether you run Nextcloud Server. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Nextcloud Server

## Related threats

- [Nextcloud federated share endpoint unauthenticated database write](https://junglewise.ai/threats/cve-2026-77167-abusing-the-federated-share-endpoint-an-attacker-can-write)
- [Nextcloud Server authorization bypass in file comments](https://junglewise.ai/threats/cve-2026-45810-nextcloud-server-authorization-bypass-in-file-comments)
- [Nextcloud Server 2FA bypass in DAV endpoints via session cookie reuse](https://junglewise.ai/threats/cve-2026-45691-nextcloud-server-2fa-bypass-in-dav-endpoints-via-session-cookie)
- [Nextcloud Server 2FA bypass via session token replay](https://junglewise.ai/threats/cve-2026-45690-nextcloud-server-2fa-bypass-via-session-token-replay)
- [Nextcloud Server hidden public link creation in Teams sharing](https://junglewise.ai/threats/cve-2026-45285-nextcloud-server-hidden-public-link-creation-in-teams-sharing)