OESA-2026-4640: xdg-dbus-proxy security update

xdg-dbus-proxy is a filtering proxy for D-Bus connections. It was originally part of the flatpak project, but it has been broken out as a standalone module to facilitate using it in other contexts. Security Fix(es):

An incorrect implementation of message filtering in xdg-dbus-proxy versions before 0.1.9 allows an attacker to bypass the intended message filtering on the D-Bus session bus by setting a reply serial number on non-reply messages. A malicious or compromised Flatpak app could use this to achieve arbitrary code execution outside its sandbox. xdg-dbus-proxy was designed to be part of the sandbox boundary for Flatpak, but it is released as a separate project and is sometimes used by other app frameworks such as Firejail.(CVE-2026-94422)