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 a data storage system for Nextcloud, a self-hosted productivity platform. When multiple requests are sent in parallel, all of them were executed even if the amount of faulty requests succeeded the limit by the time the response was sent to the client. This allowed someone to send as many requests the server could handle in parallel to bruteforce protected details instead of the configured limit, default 8. Nextcloud Server versions 25.0.7 and 26.0.2 and Nextcloud Enterprise Server versions 21.0.9.12, 22.2.10.12, 23.0.12.7, 24.0.12.2, 25.0.7 and 26.0.2 contain patches for this issue.
Nextcloud Server is an open source personal cloud server. Nextcloud Server 24.0.0 until 24.0.6 and 25.0.0 until 25.0.4, as well as Nextcloud Enterprise Server 23.0.0 until 23.0.11, 24.0.0 until 24.0.6, and 25.0.0 until 25.0.4, have an information disclosure vulnerability. A user was able to get the full data directory path of the Nextcloud server from an API endpoint. By itself this information is not problematic as it can also be guessed for most common setups, but it could speed up other unknown attacks in the future if the information is known. Nextcloud Server 24.0.6 and 25.0.4 and Nextcloud Enterprise Server 23.0.11, 24.0.6, and 25.0.4 contain patches for this issue. There are no known workarounds.
Nextcloud server is an open source home cloud implementation. In affected versions the generated fallback password when creating a share was using a weak complexity random number generator, so when the sharer did not change it the password could be guessable to an attacker willing to brute force it. It is recommended that the Nextcloud Server is upgraded to 24.0.10 or 25.0.4. This issue only affects users who do not have a password policy enabled, so enabling a password policy is an effective mitigation for users unable to upgrade.
Nextcloud server is an open source home cloud implementation. In affected versions admins of a server were able to upload a logo or a favicon and to provided a file name which was not restricted and could overwrite files in the appdata directory. Administrators may have access to overwrite these files by other means but this method could be exploited by tricking an admin into uploading a maliciously named file. It is recommended that the Nextcloud Server is upgraded to 24.0.10 or 25.0.4. Users unable to upgrade should avoid ingesting logo files from untrusted sources.