CVE-2025-66547: CWE-639: Authorization Bypass Through User-Controlled Key in nextcloud security-advisories
Nextcloud Server and Enterprise Server versions prior to 31.0.1 contain an authorization bypass vulnerability (CVE-2025-66547) that allows non-privileged users to modify tags on files they should not have access to via bulk tagging. This issue is fixed in version 31.0.1. The vulnerability has a medium severity with a CVSS score of 4.3.
AI Analysis
Technical Summary
CVE-2025-66547 is an authorization bypass vulnerability in Nextcloud Server and Enterprise Server before version 31.0.1. It allows non-privileged users to modify file tags on files without proper access permissions through bulk tagging functionality. This vulnerability is classified under CWE-639 (Authorization Bypass Through User-Controlled Key). The issue is resolved in Nextcloud version 31.0.1.
Potential Impact
The vulnerability enables non-privileged users to alter tags on files they are not authorized to access, potentially impacting data integrity by unauthorized modification of metadata. There is no direct confidentiality or availability impact reported. The CVSS score of 4.3 reflects a medium severity with low attack complexity and no user interaction required.
Mitigation Recommendations
Upgrade Nextcloud Server and Enterprise Server to version 31.0.1 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is indicated.
CVE-2025-66547: CWE-639: Authorization Bypass Through User-Controlled Key in nextcloud security-advisories
Description
Nextcloud Server and Enterprise Server versions prior to 31.0.1 contain an authorization bypass vulnerability (CVE-2025-66547) that allows non-privileged users to modify tags on files they should not have access to via bulk tagging. This issue is fixed in version 31.0.1. The vulnerability has a medium severity with a CVSS score of 4.3.
CVSS v3.1
Score 4.3medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2025-66547 is an authorization bypass vulnerability in Nextcloud Server and Enterprise Server before version 31.0.1. It allows non-privileged users to modify file tags on files without proper access permissions through bulk tagging functionality. This vulnerability is classified under CWE-639 (Authorization Bypass Through User-Controlled Key). The issue is resolved in Nextcloud version 31.0.1.
Potential Impact
The vulnerability enables non-privileged users to alter tags on files they are not authorized to access, potentially impacting data integrity by unauthorized modification of metadata. There is no direct confidentiality or availability impact reported. The CVSS score of 4.3 reflects a medium severity with low attack complexity and no user interaction required.
Mitigation Recommendations
Upgrade Nextcloud Server and Enterprise Server to version 31.0.1 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2025-12-04T15:52:26.550Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 69330c20f88dbe026cf88df2
Added to database: 12/05/2025, 16:45:20 UTC
Last enriched: 07/13/2026, 09:54:44 UTC
Last updated: 09/05/2026, 10:52:06 UTC
Views: 298
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