Vulnerability record · CVE-2025-66512 · published 5 December 2025

CVE-2025-66512: Nextcloud server cross-site scripting vulnerability

Nextcloud · Nextcloud Server

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.

6.1 CVSS 3.1 Medium EPSS 0.28% · top 81.6% CWE-80 · CWE-80CWE-79 · Cross-site scripting

6.1CVSS 3.1 base score

0.28%EPSS exploitation probability, 30 days

NoNot in CISA KEV

1Affected product versions listed by NVD

4References

17 Jun 2026Last modified by NVD

Description

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

Nextcloud Server Nextcloud

References

Link	Tags
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qcw2-p26m-9gc5	PatchVendor Advisory
https://github.com/nextcloud/viewer/commit/5044a27d61bc40c0f134298d36af91f865335b63	Patch
https://github.com/nextcloud/viewer/pull/3023	Issue Tracking
https://hackerone.com/reports/3357808	Issue TrackingVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2025-66512), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.