xdg-dbus-proxy 0.1.9 fixes sandbox escape CVE-2026-94422
xdg-dbus-proxy 0.1.9 patches sandbox escape CVE-2026-94422; every older release is vulnerable.
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Vulnerability1 · 1 read
CVE-2026-94422
D-Bus filter bypass sandbox escape in xdg-dbus-proxy
- CVSS 4.0
- 8.7 high
- EPSS
- —
- Published
- ·
- Modified
AI analysisSummaries by Vani AI
xdg-dbus-proxy before 0.1.9 implements D-Bus session-bus message filtering incorrectly, so a non-reply message that sets a reply serial number can bypass the filter. A malicious or compromised Flatpak app can use that bypass to execute arbitrary code outside its sandbox. The proxy is intended to be part of Flatpak's sandbox boundary and is also sometimes used by other frameworks such as Firejail. Any system still running a vulnerable xdg-dbus-proxy build is affected, including Flatpak and some Firejail deployments. There is no known public proof of concept, it is not listed in CISA KEV, and exploitation in the wild is not known.
What to do: Upgrade xdg-dbus-proxy to 0.1.9 or later from your distribution packages and restart Flatpak (and Firejail, if you use it) so the updated proxy is running. Until then, do not run untrusted or suspected-compromised Flatpak apps. Confirm the installed package version is 0.1.9 or newer.
| Product | Affected |
|---|---|
| freedesktop.org xdg-dbus-proxy | before 0.1.9 |
Estimated exposure
masson the order of 1 million or more Linux systems that run Flatpak (exact count of unpatched installs unknown) — xdg-dbus-proxy is the D-Bus filter used as part of the Flatpak sandbox boundary and is widely shipped or installed with Flatpak on desktop Linux, including devices such as Steam Deck and distros such as Fedora; Firejail is a smaller…
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Description · NVD
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.
- Weakness
- CWE-290
- 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X