CVE-2026-94422

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.

Red Hat's CVSSv3.1 score has been calculated from the upstream-provided CVSSv4 vector (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N). The resulting CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H vector reflects a network-exploitable flaw with low attack complexity and no privileges required, but requiring a user (via a malicious/compromised Flatpak app) to interact with the D-Bus session bus. The proxy's failure to validate reply-serial numbers on non-reply messages allows a sandboxed app to bypass its message filter and reach otherwise-blocked D-Bus interfaces, resulting in a full loss of confidentiality, integrity, and availability of the host system outside the sandbox.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Avoid running untrusted Flatpak apps and avoid running untrusted apps via other frameworks that use xdg-dbus-proxy.