CVE-2025-66547

Unknown Unknown - Not Provided

BaseFortify

Publication date: 2025-12-05

Last updated on: 2025-12-09

Assigner: GitHub, Inc.

Description

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.

CVSS Scores

EPSS Scores

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Meta Information

Published

2025-12-05

Last Modified

2025-12-09

Generated

2026-07-06

AI Q&A

2025-12-05

EPSS Evaluated

2026-07-05

NVD

CVE-2025-66547

EUVD

EUVD-2025-201447

Affected Vendors & Products

Vendor	Product	Version / Range
nextcloud	nextcloud_server	From 31.0.0 (inc) to 31.0.1 (exc)
nextcloud	nextcloud_server	From 31.0.0 (inc) to 31.0.1 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-639	The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.

Attack-Flow Graph

Executive Summary

This vulnerability in Nextcloud Server and Enterprise Server prior to version 31.0.1 allows non-privileged users to modify tags on files they should not have access to by using bulk tagging. This means users without proper permissions can change metadata tags on files, potentially affecting file organization or access control.

Impact Analysis

The vulnerability can impact you by allowing unauthorized users to alter file tags, which may lead to confusion, misclassification, or improper handling of files. Although it does not allow direct access to file contents or cause data loss, it can undermine file management and integrity within the system.

Mitigation Strategies

Upgrade Nextcloud Server or Enterprise Server to version 31.0.1 or later, as this version contains the fix for the vulnerability allowing non-privileged users to modify tags on files they should not have access to.

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