CVE-2025-66512

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

CVSS 5.4 MEDIUMEPSS 0.2%CWE-80

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 5.4EPSS 0.2%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

05 Dec 2025Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L

Affected products

nextcloud · security-advisories

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References

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qcw2-p26m-9gc5 https://github.com/nextcloud/viewer/commit/5044a27d61bc40c0f134298d36af91f865335b63 https://github.com/nextcloud/viewer/pull/3023 https://hackerone.com/reports/3357808