CVE-2025-66512
Nextcloud Server vulnerable to XSS in SVG images when opened outside of Nextcloud
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.
INFO
Published Date :
Dec. 5, 2025, 5:16 p.m.
Last Modified :
Dec. 9, 2025, 4:38 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Nextcloud Server to version 31.0.12 or later.
- Update Nextcloud Server Enterprise to version 32.0.3 or later.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-66512.
| URL | Resource |
|---|---|
| https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qcw2-p26m-9gc5 | Patch Vendor Advisory |
| https://github.com/nextcloud/viewer/commit/5044a27d61bc40c0f134298d36af91f865335b63 | Patch |
| https://github.com/nextcloud/viewer/pull/3023 | Issue Tracking |
| https://hackerone.com/reports/3357808 | Issue Tracking Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-66512 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-66512
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-66512 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2025-66512 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Dec. 09, 2025
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Added CWE CWE-79 Added CPE Configuration OR *cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:* versions from (including) 31.0.0 up to (excluding) 31.0.12 *cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:* versions from (including) 32.0.0 up to (excluding) 32.0.3 *cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:* versions from (including) 31.0.0 up to (excluding) 31.0.12 *cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:* versions from (including) 32.0.0 up to (excluding) 32.0.3 Added Reference Type GitHub, Inc.: https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qcw2-p26m-9gc5 Types: Patch, Vendor Advisory Added Reference Type GitHub, Inc.: https://github.com/nextcloud/viewer/commit/5044a27d61bc40c0f134298d36af91f865335b63 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/nextcloud/viewer/pull/3023 Types: Issue Tracking Added Reference Type GitHub, Inc.: https://hackerone.com/reports/3357808 Types: Issue Tracking, Vendor Advisory -
New CVE Received by [email protected]
Dec. 05, 2025
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L Added CWE CWE-80 Added Reference https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qcw2-p26m-9gc5 Added Reference https://github.com/nextcloud/viewer/commit/5044a27d61bc40c0f134298d36af91f865335b63 Added Reference https://github.com/nextcloud/viewer/pull/3023 Added Reference https://hackerone.com/reports/3357808