Nextcloud Android app is the Android client for Nextcloud, a self-hosted productivity platform. Prior to version 3.19.1, users can bypass a lock on the Nextcloud app on an Android device by repeatedly reopening the app. Version 3.19.1 contains a fix for the problem. There are currently no known workarounds.
CWE-287 - Improper Authentication
Improper (or broken) authentication attacks are widespread, and have accounted for many of the worst data breaches in recent years. Improper authentication attacks are a class of vulnerabilities where an attacker impersonates a legitimate user by exploiting weaknesses in either session management or credential management to gain access to the user’s account. This can result in disclosure of sensitive information, and can lead to system compromise, theft, identity theft, and fraud.