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