Nextcloud Server users can modify tags on files that do not belong to them

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-66547
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-12-05 17:16:05 UTC
Updated2026-10-18 14:10:00 UTC
DescriptionNextcloud 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.

Risk And Classification

Primary CVSS: v3.1 4.3 MEDIUM from [email protected]

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

Problem Types: CWE-639 | CWE-639 CWE-639: Authorization Bypass Through User-Controlled Key

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
3.1CNADECLARED4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Nextcloud Nextcloud Server All All All All
Application Nextcloud Nextcloud Server All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Nextcloud Security-advisories affected < 31.0.1 Not specified

References

ReferenceSourceLinkTags
hackerone.com/reports/3040887 [email protected] hackerone.com Permissions Required, Vendor Advisory
github.com/nextcloud/server/pull/51288 [email protected] github.com Issue Tracking
github.com/nextcloud/server/issues/51247 [email protected] github.com Issue Tracking
github.com/nextcloud/security-advisories/security/advisories/GHSA-hq6c-r... [email protected] github.com Patch, Vendor Advisory
github.com/nextcloud/server/commit/b44f1568f2dc97c746281d99e2342ad679e3d8a9 [email protected] github.com Patch
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