Vulnerability Report

CVE-2025-66547

Title: Non-privileged users can modify tags on files they should not have access to via bulk tagging in Nextcloud Server

Auth Bypass

Proof Of Concept

No public PoC currently indexed for CVE-2025-66547.

CWE Category CWE-639

Published Date Dec 05, 2025

Modified Date Dec 09, 2025

Exploit Status Not Found

Score 4.3 CVSS v3.1

Exploit Probability (EPSS)

0.28%

Vulnerability Summary

CVE-2025-66547: Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server and Enterprise Server prior to 31.0.1, non-privileged users can modify tags on files they should not have access to via bulk tagging. This vulnerability is fixed in 31.0.1.

Impacted Vendors

nextcloud 1

Reference Links

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-hq6c-r898-fgf2 https://github.com/nextcloud/server/commit/b44f1568f2dc97c746281d99e2342ad679e3d8a9 https://github.com/nextcloud/server/issues/51247 https://github.com/nextcloud/server/pull/51288 https://hackerone.com/reports/3040887

CVSS v3.1

Source Entity [email protected]

Severity MEDIUM

4.3

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

UNCHANGED

RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2025-66547 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

December 09, 2025 MODIFIED

Vulnerability data or affected products updated.

December 09, 2025 MODIFIED

Vulnerability data updated via NVD.

December 05, 2025 PUBLISHED

Vulnerability first announced in NVD.

Attack Vector Matrix

Access Vector NETWORK

Complexity LOW

Privileges N/A

Interaction NONE

CVSS Vector String


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

Affected Stack

No specific products linked.