A missing check in Nextcloud Server 14.0.3 could give recipient the possibility to extend the expiration date of a share they received.

Nextcloud Server before 9.0.55 and 10.0.2 suffers from a creation of folders in read-only folders despite lacking permissions issue. Due to a logical error in the file caching layer an authenticated adversary is able to create empty folders inside a shared folder. Note that this only affects folders and files that the adversary has at least read-only permissions for.

Improper access control in Nextcloud Deck 1.0.0 allowed an attacker to inject tasks into other users decks.

Nextcloud Server before 9.0.52 & ownCloud Server before 9.0.4 are not properly verifying edit check permissions on WebDAV copy actions. The WebDAV endpoint was not properly checking the permission on a WebDAV COPY action. This allowed an authenticated attacker with access to a read-only share to put new files in there. It was not possible to modify existing files.

Improper Authentication in Nextcloud Server prior to version 12.0.3 would allow an attacker that obtained user credentials to bypass the 2 Factor Authentication.

Nextcloud Mail is a mail app for Nextcloud. In versions prior to 1.9.6, the Nextcloud Mail application does not, by default, render images in emails to not leak the read state. The privacy filter failed to filter images with a `background-image` CSS attribute. Note that the images were still passed through the Nextcloud image proxy, and thus there was no IP leakage. The issue was patched in version 1.9.6 and 1.10.0. No workarounds are known to exist.

Nextcloud Richdocuments in an open source self hosted online office. Nextcloud uses the WOPI ("Web Application Open Platform Interface") protocol to communicate with the Collabora Editor, the communication between these two services was not protected by a credentials or IP check. Whilst this does not result in gaining access to data that the user has not yet access to, it can result in a bypass of any enforced watermark on documents as described on the [Nextcloud Virtual Data Room](https://nextcloud.com/virtual-data-room/) website and [our documentation](https://portal.nextcloud.com/article/nextcloud-and-virtual-data-room-configuration-59.html). The Nextcloud Richdocuments releases 3.8.3 and 4.2.0 add an additional admin settings for an allowlist of IP addresses that can access the WOPI API. We recommend upgrading and configuring the allowlist to a list of Collabora servers. There is no known workaround. Note that this primarily results a bypass of any configured watermark or download protection using File Access Control. If you do not require or rely on these as a security feature no immediate action is required on your end.

The document application in ownCloud Server before 6.0.3 uses sequential values for the file_id, which allows remote authenticated users to enumerate shared files via unspecified vectors.

An attacker is logged in as a normal user and can somehow make admin to delete shared folders in ownCloud Server before 10.0.2.

A missing file type check in Nextcloud Contacts 3.2.0 allowed a malicious user to upload any file as avatars.

Nextcloud mail is a Mail app for the Nextcloud home server product. Versions of Nextcloud mail prior to 1.12.2 were found to be missing user account ownership checks when performing tasks related to mail attachments. Attachments may have been exposed to incorrect system users. It is recommended that the Nextcloud Mail app is upgraded to 1.12.2. There are no known workarounds for this issue. ### Workarounds No workaround available ### References * [Pull request](https://github.com/nextcloud/mail/pull/6600) * [HackerOne](https://hackerone.com/reports/1579820) ### For more information If you have any questions or comments about this advisory: * Create a post in [nextcloud/security-advisories](https://github.com/nextcloud/security-advisories/discussions) * Customers: Open a support ticket at [support.nextcloud.com](https://support.nextcloud.com)

Nextcloud Deck is a Kanban-style project & personal management tool for Nextcloud. In versions prior to 1.4.8, 1.5.6, and 1.6.1, an authenticated user can move stacks with cards from their own board to a board of another user. The Nextcloud Deck app contains a patch for this issue in versions 1.4.8, 1.5.6, and 1.6.1. There are no known currently-known workarounds available.

Dangling remote share attempts in Nextcloud 16 allow a DNS pollution when running long.

Improper permissions preservation in Nextcloud Server 16.0.1 causes sharees to be able to reshare with write permissions when sharing the mount point of a share they received, as a public link.

Nextcloud Server before 9.0.55 and 10.0.2 suffers from a bypass in the quota limitation. Due to not properly sanitizing values provided by the `OC-Total-Length` HTTP header an authenticated adversary may be able to exceed their configured user quota. Thus using more space than allowed by the administrator.

Nextcloud Server before 9.0.54 and 10.0.0 suffers from an improper authorization check on removing shares. The Sharing Backend as implemented in Nextcloud does differentiate between shares to users and groups. In case of a received group share, users should be able to unshare the file to themselves but not to the whole group. The previous API implementation simply unshared the file to all users in the group.

Nextcloud Mail before 1.9.5 suffers from improper access control due to a missing permission check allowing other authenticated users to create mail aliases for other users.

Improper Input Validation in Nextcloud Server 15.0.7 allows group admins to create users with IDs of system folders.

ownCloud Server before 10.3.0 allows an attacker, who has received non-administrative access to a group share, to remove everyone else's access to that share.

Nextcloud Server before 12.0.8 and 13.0.3 suffers from improper checks of dropped permissions for incoming shares allowing a user to still request previews for files it should not have access to.

Nextcloud Desktop is the desktop sync client for Nextcloud. In versions of Nextcloud Desktop prior to 3.15, 3rdparty applications already installed on a user machine can create link shares for almost all data via the socket API. These shares can then be easily sent off to an external service. Nextcloud Desktop fixes the issue in version 3.15. No known workarounds are available.

Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server prior to 29.0.13, 30.0.7, and 31.0.1 and Nextcloud Enterprise Server prior to 26.0.13.13, 27.1.11.13, 28.0.14.4, 29.0.13, 30.0.7, and 31.0.1, an attacker on a multi-user system may read temporary files from Nextcloud running with a different user account, or run a symlink attack. Nextcloud Server versions 29.0.13, 30.0.7, and 31.0.1 and Nextcloud Enterprise Server 26.0.13.13, 27.1.11.13, 28.0.14.4, 29.0.13, 30.0.7, and 31.0.1 fix the issue. No known workarounds are available.

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. In Nextcloud Server prior to versions 26.0.9 and 27.1.4; as well as Nextcloud Enterprise Server prior to versions 23.0.12.13, 24.0.12.9, 25.0.13.4, 26.0.9, and 27.1.4; when an attacker manages to get access to an active session of another user via another way, they could delete and modify workflows by sending calls directly to the API bypassing the password confirmation shown in the UI. Nextcloud Server versions 26.0.9 and 27.1.4 and Nextcloud Enterprise Server versions 23.0.12.13, 24.0.12.9, 25.0.13.4, 26.0.9, and 27.1.4 contain a patch for this issue. No known workarounds are available.

Nextcloud Server is a Nextcloud package that handles data storage. A vulnerability in federated share exists in versions prior to 19.0.11, 20.0.10, and 21.0.2. An attacker can gain access to basic information about users of a server by accessing a public link that a legitimate server user added as a federated share. This happens because Nextcloud supports sharing registered users with other Nextcloud servers, which can be done automatically when selecting the "Add server automatically once a federated share was created successfully" setting. The vulnerability is patched in versions 19.0.11, 20.0.10, and 21.0.2 As a workaround, disable "Add server automatically once a federated share was created successfully" in the Nextcloud settings.

Nextcloud Mail is a mail app for the Nextcloud platform. A missing permission check in Nextcloud Mail before 1.4.3 and 1.8.2 allows another authenticated users to access mail metadata of other users. Versions 1.4.3 and 1.8.2 contain patches for this vulnerability; no workarounds other than the patches are known to exist.

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 25.0.0 and prior to versions 25.0.11, 26.0.6, and 27.1.0 of Nextcloud Server and Nextcloud Enterprise Server, admins can change authentication details of user configured external storage. Nextcloud Server and Nextcloud Enterprise Server versions 25.0.11, 26.0.6, and 27.1.0 contain a patch for this issue. No known workarounds are available.

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 Docker image of ownCloud Server through 10.11 contains a misconfiguration that renders the trusted_domains config useless. This could be abused to spoof the URL in password-reset e-mail messages.

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 24.0.4 and prior to versions 25.0.9, 26.0.4, and 27.0.1, when a folder with images or an image was shared without download permissions, the user could add the image inline into a text file and download it. Nextcloud Server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1 contain a patch for this issue. No known workarounds are available.

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 25.0.0 and prior to versions 25.0.9, 26.0.4, and 27.0.1, unauthenticated users could send a DAV request which reveals whether a calendar or an address book with the given identifier exists for the victim. Nextcloud Server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 25.0.9, 26.0.4, and 27.0.1 contain a patch for this issue. No known workarounds are available.

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 19.0.0 and prior to versions 19.0.13.10, 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.8, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1, a malicious user could delete any personal or global external storage, making them inaccessible for everyone else as well. Nextcloud server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 19.0.13.10, 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.9, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1 contain a patch for this issue. As a workaround, disable app files_external. This also makes the external storage inaccessible but retains the configurations until a patched version has been deployed.

The user_openid app in ownCloud Server before 5.0.15 allows remote attackers to obtain access by leveraging an insecure OpenID implementation.

A missing user check in Nextcloud prior to 20.0.6 inadvertently populates a user's own credentials for other users external storage configuration when not already configured yet.

NextCloud Server and NextCloud Enterprise Server provide file storage for Nextcloud, a self-hosted productivity platform. In NextCloud Server versions 25.0.0 until 25.0.7 and 26.0.0 until 26.0.2 and Nextcloud Enterprise Server versions 21.0.0 until 21.0.9.12, 22.0.0 until 22.2.10.12, 23.0.0 until 23.0.12.7, 24.0.0 until 24.0.12.2, 25.0.0 until 25.0.7, and 26.0.0 until 26.0.2, when two server are registered as trusted servers for each other and successfully exchanged the share secrets, the malicious server could modify or delete VCards in the system addressbook on the origin server. This would impact the available and shown information in certain places, such as the user search and avatar menu. If a manipulated user modifies their own data in the personal settings the entry is fixed again. Nextcloud Server n 25.0.7 and 26.0.2 and Nextcloud Enterprise Server 21.0.9.12, 22.2.10.12, 23.0.12.7, 24.0.12.2, 25.0.7, and 26.0.2 contain a patch for this issue. A workaround is available. Remove all trusted servers in the "Administration" > "Sharing" settings `…/index.php/settings/admin/sharing`. Afterwards, trigger a recreation of the local system addressbook with the following `occ dav:sync-system-addressbook`.

Nextcloud Server is an open source personal cloud server. Prior to versions 24.0.7 and 25.0.1, disabled download shares still allow download through preview images. Images could be downloaded and previews of documents (first page) can be downloaded without being watermarked. Versions 24.0.7 and 25.0.1 contain a fix for this issue. No known workarounds are available.

Nextcloud Server is the file server software for Nextcloud, a self-hosted productivity platform. Nextcloud Server and Nextcloud Enterprise Server prior to versions 23.0.9 and 24.0.5 are vulnerable to exposure of information that cannot be controlled by administrators without direct database access. Versions 23.0.9 and 24.0.5 contains patches for this issue. No known workarounds are available.

Improper access control in Nextcloud Social app version 0.3.1 allowed to read posts of any user.

Improper access control in Nextcloud Deck 0.8.0 allowed an attacker to reshare boards shared with them with more permissions than they had themselves.

A missing access control check in Nextcloud Server < 18.0.1, < 17.0.4, and < 16.0.9 causes hide-download shares to be downloadable when appending /download to the URL.

Improper access control in Groupfolders app 4.0.3 allowed to delete hidden directories when when renaming an accessible item to the same name.

Nextcloud Server is a self hosted personal cloud system. After a user received a share with some files inside being blocked by the files access control, the user would still be able to copy the intermediate folder inside Nextcloud allowing them to afterwards potentially access the blocked files depending on the user access control rules. It is recommended that the Nextcloud Server is upgraded to 27.1.9, 28.0.5 or 29.0.0 and Nextcloud Enterprise Server is upgraded to 21.0.9.18, 22.2.10.23, 23.0.12.18, 24.0.12.14, 25.0.13.9, 26.0.13.3, 27.1.9, 28.0.5 or 29.0.0.

A bug in Nextcloud Server 14.0.4 could expose more data in reshared link shares than intended by the sharer.

Nextcloud is a personal home server system. Depending on the set up tags and other workflows this issue can be used to limit access of others or being able to grant them access when there are system tag based files access control or files retention rules. It is recommended that the Nextcloud Server is upgraded to 24.0.11 or 25.0.5, the Nextcloud Enterprise Server to 21.0.9.11, 22.2.10.11, 23.0.12.6, 24.0.11 or 25.0.5, and the Nextcloud Files automated tagging app to 1.11.1, 1.12.1, 1.13.1, 1.14.2, 1.15.3 or 1.16.1. Users unable to upgrade should disable all workflow related apps. Users are advised to upgrade.

Nextcloud server is an open source home cloud implementation. In affected versions users that should not be able to download a file can still download an older version and use that for uncontrolled distribution. This issue has been addressed in versions 24.0.10 and 25.0.4. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Nextcloud richdocuments is a Nextcloud app integrating the office suit Collabora Online. In affected versions the secure view feature of the rich documents app can be bypassed by using unprotected internal API endpoint of the rich documents app. It is recommended that the Nextcloud Office app (richdocuments) is upgraded to 8.0.0-beta.1, 7.0.2 or 6.3.2. Users unable to upgrade may mitigate the issue by taking steps to restrict the ability to download documents. This includes ensuring that the `WOPI configuration` is configured to only serve documents between Nextcloud and Collabora. It is highly recommended to define the list of Collabora server IPs as the allow list within the Office admin settings of Nextcloud.

richdocuments is the repository for NextCloud Collabra, the app for Nextcloud Office collaboration. Prior to versions 6.0.0, 5.0.4, and 4.2.6, a user could be tricked into working against a remote Office by sending them a federated share. richdocuments versions 6.0.0, 5.0.4 and 4.2.6 contain a fix for this issue. There are currently no known workarounds available.

Nextcloud Server is a self hosted personal cloud system. An attacker with read-only access to a file is able to restore older versions of a document when the files_versions app is enabled. It is recommended that the Nextcloud Server is upgraded to 26.0.12, 27.1.7 or 28.0.3 and that the Nextcloud Enterprise Server is upgraded to 23.0.12.16, 24.0.12.12, 25.0.13.6, 26.0.12, 27.1.7 or 28.0.3.

Nextcloud Android is the Android client for Nextcloud, a self-hosted productivity platform. Prior to version 3.19.0, sensitive tokens, images, and user related details exist after deletion of a user account. This could result in misuse of the former account holder's information. Nextcloud Android version 3.19.0 contains a patch for this issue. There are no known workarounds available.