Content Security Bypass in Nextcloud Server by Malicious SVG Interaction
CVE-2025-66512

5.4MEDIUM

Key Information:

Vendor

Nextcloud
Status
Security-advisories
Vendor
CVE Published:
5 December 2025

What is CVE-2025-66512?

A vulnerability in Nextcloud Server and Nextcloud Server Enterprise allows attackers to bypass the content security policy. Malicious users can exploit this flaw by tricking unsuspecting users into viewing an uploaded SVG file outside of the controlled environment of the Nextcloud platform. The absence of proper sanitization measures contributes to this vulnerability, potentially exposing users to a range of security risks.

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Deploy the Patch

Affected Version(s)

security-advisories >= 32.0.0beta1, < 32.0.3 < 32.0.0beta1, 32.0.3

security-advisories < 31.0.12 < 31.0.12

References

https://github.com/nextcloud/security-advisories/security...
x_refsource_CONFIRM
https://github.com/nextcloud/viewer/pull/3023
x_refsource_MISC
https://github.com/nextcloud/viewer/commit/5044a27d61bc40...
x_refsource_MISC

CVSS V3.1

Score:
5.4
Severity:
MEDIUM
Confidentiality:
None
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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