Tasks.org vulnerable to data exfiltration by malicous app or adb

Summary

The Tasks.org Android app is an open-source app for to-do lists and reminders. The Tasks.org app uses the activity `ShareLinkActivity.kt` to handle "share" intents coming from other components in the same device and convert them to tasks. Those intents may contain arbitrary file paths as attachments, in which case the files pointed by those paths are copied in the app's external storage directory. Prior to versions 12.7.1 and 13.0.1, those paths were not validated, allowing a malicious or compromised application in the same device to force Tasks.org to copy files from its internal storage to its external storage directory, where they became accessible to any component with permission to read the external storage. This vulnerability can lead to sensitive information disclosure. All information in the user's notes and the app's preferences, including the encrypted credentials of CalDav integrations if enabled, could be accessed by third party applications installed on the same device. This issue was fixed in versions 12.7.1 and 13.0.1. There are no known workarounds.