Nextcloud Server is a Nextcloud package that handles data storage. In versions prior to 19.0.11, 20.0.10, and 21.0.2, an attacker is able to receive write/read privileges on any Federated File Share. Since public links can be added as federated file share, this can also be exploited on any public link. Users can upgrade to patched versions (19.0.11, 20.0.10 or 21.0.2) or, as a workaround, disable federated file sharing.

Nextcloud Server is a Nextcloud package that handles data storage. Nextcloud Server versions prior to 19.0.11, 20.0.10, or 21.0.2 send user IDs to the lookup server even if the user has no fields set to published. The vulnerability is patched in versions 19.0.11, 20.0.10, and 21.0.2; no workarounds outside the updates are known to exist.

Nextcloud Server prior to 20.0.6 is vulnerable to reflected cross-site scripting (XSS) due to lack of sanitization in `OC.Notification.show`.

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 prior to 20.0.0 stores passwords in a recoverable format even when external storage is not configured.

A missing link validation in Nextcloud Server before 20.0.2, 19.0.5, 18.0.11 allows execution of a stored XSS attack using Internet Explorer when saving a 'javascript:' URL in markdown format.

A wrong check in Nextcloud Server 19 and prior allowed to perform a denial of service attack when resetting the password for a user.

A missing input validation in Nextcloud Server before 20.0.2, 19.0.5, 18.0.11 allows users to store unlimited data in workflow rules causing load and potential DDoS on later interactions and usage with those rules.

Insufficient protection of the server-side encryption keys in Nextcloud Server 19.0.1 allowed an attacker to replace the encryption keys.

Insufficient protection of the server-side encryption keys in Nextcloud Server 19.0.1 allowed an attacker to replace the public key to decrypt them later on.

A cryptographic issue in Nextcloud Server 19.0.1 allowed an attacker to downgrade the encryption scheme and break the integrity of encrypted files.

A wrong configuration in Nextcloud Server 19.0.1 incorrectly made the user feel the passwordless WebAuthn is also a two factor verification by asking for the PIN of the passwordless WebAuthn but not verifying it.

A logic error in Nextcloud Server 19.0.0 caused a plaintext storage of the share password when it was given on the initial create API call.

A too small set of random characters being used for encryption in Nextcloud Server 18.0.4 allowed decryption in shorter time than intended.

An outdated 3rd party library in the Files PDF viewer for Nextcloud Server 18.0.2 caused a Cross-site scripting vulnerability when opening a malicious PDF.

An Insecure direct object reference vulnerability in Nextcloud Server 18.0.2 allowed an attacker to remote wipe devices of other users when sending a malicious request directly to the endpoint.

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.

A missing check for IPv4 nested inside IPv6 in Nextcloud server < 17.0.1, < 16.0.7, and < 15.0.14 allowed a Server-Side Request Forgery (SSRF) vulnerability when subscribing to a malicious calendar URL.

Improper authorization in Nextcloud server 17.0.0 causes leaking of previews and files when a file-drop share link is opened via the gallery app.

An authenticated server-side request forgery in Nextcloud server 16.0.1 allowed to detect local and remote services when adding a new subscription in the calendar application.