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.
Nextcloud server is a self hosted personal cloud system. In affected versions OAuth codes did not expire. When an attacker would get access to an authorization code they could authenticate at any time using the code. As of version 28.0.0 OAuth codes are invalidated after 10 minutes and will no longer be authenticated. To exploit this vulnerability an attacker would need to intercept an OAuth code from a user session. It is recommended that the Nextcloud Server is upgraded to 28.0.0. There are no known workarounds for this vulnerability.
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.