XDG Desktop Portal vulnerabilities

In XDG Desktop Portal before version 1.22.1, malicious sandboxed applications can use FileTransfer.RetrieveFiles to redirect drag-and-drop and copy-paste data intended for other applications to themselves. Access tokens were generated with g_random_int or g_uuid_string_random based on Mersenne Twister, allowing recovery of PRNG state and prediction of subsequent tokens.

In XDG Desktop Portal before version 1.22.1, malicious sandboxed applications can use FileChooser.SaveFiles to gain arbitrary file access to non-existing files on the host (limited to files the user has access to). Filenames are not validated by the frontend or common backends, which are supposed to check that the file does not already exist.

Flatpak xdg-desktop-portal before 1.20.4 and 1.21.x before 1.21.1 allows any Flatpak app to trash any file in the host context via a symlink attack on g_file_trash. The vulnerability is fixed in 1.20.4 and 1.21.1.