CVE-2025-66512
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-12-05

Last updated on: 2025-12-09

Assigner: GitHub, Inc.

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.
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Meta Information
Published
2025-12-05
Last Modified
2025-12-09
Generated
2026-06-16
AI Q&A
2025-12-05
EPSS Evaluated
2026-06-15
NVD
CVE-2025-66512
EUVD
EUVD-2025-201449
Affected Vendors & Products
Showing 4 associated CPEs
Vendor Product Version / Range
nextcloud nextcloud_server From 31.0.0 (inc) to 31.0.12 (exc)
nextcloud nextcloud_server From 31.0.0 (inc) to 31.0.12 (exc)
nextcloud nextcloud_server From 32.0.0 (inc) to 32.0.3 (exc)
nextcloud nextcloud_server From 32.0.0 (inc) to 32.0.3 (exc)
Helpful Resources
Exploitability
CWE
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KEV
KEV Icon
CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
CWE-80 The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special characters such as "<", ">", and "&" that could be interpreted as web-scripting elements when they are sent to a downstream component that processes web pages.
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Executive Summary

This vulnerability in Nextcloud Server allows a malicious user to bypass the content security policy by tricking another user into viewing a specially crafted SVG file outside of the Nextcloud Server's web page. The issue is due to missing sanitization of the SVG content in versions prior to 31.0.12 and 32.0.3.

Impact Analysis

The vulnerability can lead to a partial security bypass where an attacker can circumvent content security policies, potentially leading to limited integrity and availability impacts on the affected system. This could allow malicious content to be executed or displayed in unintended ways when a user views a manipulated SVG file.

Mitigation Strategies

To mitigate this vulnerability, you should immediately upgrade your Nextcloud Server or Nextcloud Enterprise Server to version 31.0.12 or 32.0.3 or later, where the issue has been patched. There are no available workarounds, so applying the official update is the recommended action to prevent exploitation. [3]

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