CVE-2025-66512

Nextcloud Server vulnerable to XSS in SVG images when opened outside of Nextcloud

MEDIUM
6.1
CVSS Score
Published: December 5, 2025 at 04:22 PM UTC
Updated: October 18, 2026 at 02:10 PM UTC
2 products affected across 1 vendorNextcloud/serversecurity-advisories

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Severity
MEDIUM6.1
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

31.0.0 ≤ v < 31.0.1232.0.0 ≤ v < 32.0.3

References (4)

x_refsource_MISCIssue Tracking
Source: cverecord
https://github.com/nextcloud/viewer/pull/3023
x_refsource_MISCIssue TrackingVendor Advisory
Source: cverecord
https://hackerone.com/reports/3357808

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-80CWE-79

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