A flaw in XDG Desktop Portal allowed sandboxed applications to abuse the FileTransfer.RetrieveFiles method so that drag‑and‑drop and copy‑paste data intended for other applications could be redirected to the malicious app. The portal generated transfer tokens using a predictable pseudo‑random number generator based on GLib’s GRand. By predicting these tokens, an attacker could access files that were not intended for them. The vulnerability is a classic case of information disclosure caused by weak randomness.

Flatpak’s XDG Desktop Portal, version 1.22.0 and earlier, is affected. Users running sandboxed applications that rely on the portal for file transfer operations are at risk.

The CVSS score is 8.3, indicating a high severity. The EPSS score is not available, and the vulnerability is not listed in the CISA KEV catalog. Exploitation requires a malicious sandboxed application; if such an app runs locally, it can predict the portal’s transfer token stream and capture data from other applications. The attack vector is local, constrained to sandboxed app execution, but the impact is non‑trivial because it enables data theft across application boundaries.