Nextcloud Groupfolders provides admin-configured folders shared by everyone in a group or team. Prior to 14.0.11, 15.3.12, 16.0.15, 17.0.14, 18.1.8, 19.1.8, and 20.1.2, a user with read-only permission can restore a file from the trash bin. This vulnerability is fixed in 14.0.11, 15.3.12, 16.0.15, 17.0.14, 18.1.8, 19.1.8, and 20.1.2.
The Nextcloud Approval app allows approval or disapproval of files in the sidebar. Prior to 1.3.1 and 2.5.0, an authenticated user listed as a requester in a workflow can set another user’s file into the “pending approval” without access to the file by using the numeric file id. This vulnerability is fixed in 1.3.1 and 2.5.0.
Nextcloud Mail is the mail app for Nextcloud, a self-hosted productivity platform. Prior to 5.5.3, a stored HTML injection in the Mail app's message list allowed an authenticated user to inject HTML into the email subjects. Javascript was correctly blocked by the content security policy of the Nextcloud Server code.
Nextcloud Deck is a kanban style organization tool aimed at personal planning and project organization for teams integrated with Nextcloud. Prior to 1.14.6 and 1.15.2, a bug in the permission logic allowed users with "Can share" permission to modify the permissions of other recipients. This vulnerability is fixed in 1.14.6 and 1.15.2.
Nextcloud Deck is a kanban style organization tool aimed at personal planning and project organization for teams integrated with Nextcloud. Prior to 1.12.7, 1.14.4, and 1.15.1, file extension can be spoofed by using RTLO characters, tricking users into download files with a different extension than what is displayed. This vulnerability is fixed in 1.12.7, 1.14.4, and 1.15.1.
CVE-2025-66553 is a medium-severity authorization bypass vulnerability in Nextcloud Tables versions prior to 0.8.7 and between 0.9.0-beta.1 and 0.9.4. Authenticated users could manipulate numeric IDs in requests to view metadata of columns in other users' tables, exposing potentially sensitive schema information. This vulnerability does not allow modification or deletion of data, nor does it require user interaction beyond authentication.
Nextcloud Tables allows you to create your own tables with individual columns. Prior to 0.8.6 and 0.9.3, a malicious user was able to create their own table and then move a column to a victims table. This vulnerability is fixed in 0.8.6 and 0.9.3.
CVE-2025-66513 is a medium severity authorization bypass vulnerability in Nextcloud Tables versions prior to 0.8.9, 0.9.6, and 1.0.1. It allows unauthorized users to access information about which tables are shared with which groups or users and their permissions, due to insufficient access control on user-controlled keys. Exploitation requires network access and some user interaction but no privileges. The vulnerability impacts confidentiality but not integrity or availability.
Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.17 and 5.2.4, when a malicious user creates a calendar event with a crafted attachment that links to a download link of a file on the same Nextcloud server, the file would be downloaded without the user confirming the action. This vulnerability is fixed in 4.7.17 and 5.2.4.
Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.19, 5.5.6, and 6.0.1, the calendar app allowed blindly booking appointments with a squential ID without known the appointment token. This vulnerability is fixed in 4.7.19, 5.5.6, and 6.0.1.
Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server and Enterprise Server prior to 30.0.9 and 31.0.1, incorrect path handling with groupfolders caused the admin_audit app to not properly log all actions on files and folders inside groupfolders. This vulnerability is fixed in Nextcloud Server and Enterprise Server prior to 30.0.9 and 31.0.1.
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.
CVE-2025-66511 is a medium severity vulnerability in Nextcloud Calendar versions prior to 6.0.3 where participant tokens for meeting proposals are generated using insufficiently random values. This weakness allows attackers to compute valid participant tokens, enabling unauthorized access to meeting proposal details and the ability to submit dates. The vulnerability arises from the use of a hash function rather than a cryptographically secure random number generator. Exploitation requires no authentication or user interaction but has a higher attack complexity. The issue is fixed in version 6.0.3. No known exploits are currently reported in the wild.
Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server prior to 31.0.10 and 32.0.1 and Nextcloud Enterprise Server prior to 28.0.14.11, 29.0.16.8, 30.0.17.3, and 31.0.10, contacts search allowed to retrieve personal data of other users (emails, names, identifiers) without proper access control. This allows an authenticated user to retrieve information about accounts that are not related or added as contacts.
Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server and Server Enterprise prior to 31.0.12 and 32.0.3, a missing sanitization allowed malicious users to circumvent the content security policy when a malicious user manages to trick a user it viewing an uploaded SVG outside of the Nextcloud Servers web page.
Nextcloud Tables allows you to create your own tables with individual columns. Prior 0.7.6, 0.8.8, and 0.9.5, when importing a table, a user was able to specify files on the server and when their format is supported by the used PhpSpreadsheet library they would be included and their content leaked to the user. It is recommended that the Nextcloud Tables app is upgraded to 0.7.6, 0.8.8 or 0.9.5.
Nextcloud guests app is a utility to create guest users which can only see files shared with them. In affected versions users were able to load the first page of apps they were actually not allowed to access. Depending on the selection of apps installed this may present a permissions bypass. It is recommended that the Guests app is upgraded to 2.4.1, 2.5.1 or 3.0.1. There are no known workarounds for this vulnerability.
Nextcloud files Zip app is a tool to create zip archives from one or multiple files from within Nextcloud. In affected versions users can download "view-only" files by zipping the complete folder. It is recommended that the Files ZIP app is upgraded to 1.2.1, 1.4.1, or 1.5.0. Users unable to upgrade should disable the file zip app.
Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 25.0.0 and prior to versions 25.0.13, 26.0.8, and 27.1.3 of Nextcloud Server and starting in version 20.0.0 and prior to versions 20.0.14.16, 21.0.9.13, 22.2.10.15, 23.0.12.12, 24.0.12.8, 25.0.13, 26.0.8, and 27.1.3 of Nextcloud Enterprise Server, a malicious user could update any personal or global external storage, making them inaccessible for everyone else as well. Nextcloud Server 25.0.13, 26.0.8, and 27.1.3 and Nextcloud Enterprise Server is upgraded to 20.0.14.16, 21.0.9.13, 22.2.10.15, 23.0.12.12, 24.0.12.8, 25.0.13, 26.0.8, and 27.1.3 contain a patch for this issue. As a workaround, disable app files_external. This workaround also makes the external storage inaccessible but retains the configurations until a patched version has been deployed.
The Nextcloud Desktop Client is a tool to synchronize files from Nextcloud Server. Starting with version 3.0.0 and prior to version 3.6.5, a malicious server administrator can recover and modify the contents of end-to-end encrypted files. Users should upgrade the Nextcloud Desktop client to 3.6.5 to receive a patch. No known workarounds are available.