Skip to content

XSS in SVG images when opened outside of Nextcloud

Moderate
nickvergessen published GHSA-qcw2-p26m-9gc5 Dec 5, 2025

Package

Server (Nextcloud)

Affected versions

>= 31.0.0, >= 32.0.0

Patched versions

31.0.12, 32.0.3
Server (Nextcloud Entreprise)
>= 31.0.0, >= 32.0.0
31.0.12, 32.0.3

Description

Impact

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.

Patches

It is recommended that the Nextcloud Server is upgraded to 31.0.12 or 32.0.3
It is recommended that the Nextcloud Enterprise Server is upgraded to 31.0.12 or 32.0.3

Workarounds

  • No workaround available

References

For more information

If you have any questions or comments about this advisory:

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L

CVE ID

CVE-2025-66512

Weaknesses

Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)

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. Learn more on MITRE.