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CVE-2025-66512

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

Published: Dec 5, 2025Updated: Dec 9, 2025 Sources: CVE List NVD BDUCWE-80
NVD MITRE
5.4CVSSMEDIUM
EPSS Score
0.2%
Top 86.1%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:RS:UC:NI:LA:L
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:LIntegrity
Low
A:LAvailability
Low
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Weaknesses

CWE-80CWE-79

Affected Products

security-advisoriesnextcloud
SaaSSaaS Service
Cloud & SaaS / saas-application
nextcloud servernextcloud
SaaSSaaS Service
Cloud & SaaS / saas-application
РЕД ОСООО «Ред Софт»
On-premOS
Operating Systems / linux-distro
NextcloudNextcloud GmbH
SaaS
Cloud & SaaS / saas-application
nextcloudoss-projectDECloud & SaaSaka nextcloud server
ооо «ред софт»commercialRUOperating Systemsaka red soft
nextcloud gmbhcommercialDECloud & SaaSaka nextcloud server, nextcloud enterprise server, nextcloud calendar

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Execution
Initial Access
View detailed technique mapping

References

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qcw2-p26m-9gc5
github.com
https://github.com/nextcloud/viewer/pull/3023
github.com
https://github.com/nextcloud/viewer/commit/5044a27d61bc40c0f134298d36af91f865335b63
github.com
and 7 more references View all →

Timeline

Published
Dec 5, 2025
Last Updated
Dec 9, 2025

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