CVE-2025-66512

Name: CVE-2025-66512
Creator: NVD / NIST
Published: 2025-12-05T17:16:04.98+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.1/10EPSS 0.23%

Last modified Jun 17, 2026

CVE-2025-66512 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. 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.. EPSS estimates a 0.23% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

0.23%

14.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Nextcloud	Nextcloud Server	>= 31.0.0, < 31.0.12
Nextcloud	Nextcloud Server	>= 32.0.0, < 32.0.3

References

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qcw2-p26m-9gc5Patch, Vendor Advisory
https://github.com/nextcloud/viewer/commit/5044a27d61bc40c0f134298d36af91f865335b63Patch
https://github.com/nextcloud/viewer/pull/3023Issue Tracking
https://hackerone.com/reports/3357808Issue Tracking, Vendor Advisory

Timeline

Published: Dec 5, 2025
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2025-66512?

How severe is CVE-2025-66512?

CVE-2025-66512 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 0.23% probability of exploitation in the next 30 days.

How do I fix CVE-2025-66512?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-66512?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST