Bug 2542244

Summary:	CVE-2026-94422 xdg-dbus-proxy: xdg-dbus-proxy: message filtering bypass via reply serial allows sandbox escape [fedora-all]
Product:	[Fedora] Fedora	Reporter:	Melissa Ing <meing>
Component:	xdg-dbus-proxy	Assignee:	Matthias Clasen <mclasen>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	unspecified
Version:	rawhide	CC:	gnome-sig, kalevlember, mclasen, renner0
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["a94594c9-8169-42b8-9713-a8a60a855983"]}
Fixed In Version:	xdg-dbus-proxy-0.1.9-1.fc44 xdg-dbus-proxy-0.1.9-1.fc45 xdg-dbus-proxy-0.1.9-1.fc43	Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2026-10-01 01:12:41 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Melissa Ing 2026-09-27 22:41:13 UTC

Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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.

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.

Impact: A malicious or compromised Flatpak app could achieve arbitrary code execution outside its sandbox. If other app frameworks rely on xdg-dbus-proxy in the same way that Flatpak does, then they will have an equivalent vulnerability until xdg-dbus-proxy is updated.

Fixed in 0.1.9 by commits:
* e5702fca4dba9600721921fbca2dbc39dc5ca400 "proxy: Don't assume that only returns and errors have a reply-serial"
* fc027f759316fb2a6c45648200b6f100202eb84e "proxy: Make it clearer which direction messages are going in"
* e4465a0dfe96da3b39929a30a1ac3a22b16223e3 "proxy: Only allow replies to go to the correct destination"

Reported by @refi64.

Reference: https://github.com/flatpak/xdg-dbus-proxy/security/advisories/GHSA-2cgv-pwcq-wvpq

Comment 1 Fedora Update System 2026-09-28 11:23:51 UTC

FEDORA-2026-f10257ca80 (xdg-dbus-proxy-0.1.9-1.fc45) has been submitted as an update to Fedora 45.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-f10257ca80

Comment 2 Fedora Update System 2026-09-28 11:29:10 UTC

FEDORA-2026-93f562a43f (xdg-dbus-proxy-0.1.9-1.fc44) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-93f562a43f

Comment 3 Fedora Update System 2026-09-28 11:38:48 UTC

FEDORA-2026-e1cac11588 (xdg-dbus-proxy-0.1.9-1.fc43) has been submitted as an update to Fedora 43.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-e1cac11588

Comment 4 Fedora Update System 2026-09-29 01:34:32 UTC

FEDORA-2026-f10257ca80 has been pushed to the Fedora 45 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-f10257ca80`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-f10257ca80

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 5 Fedora Update System 2026-09-29 01:54:27 UTC

FEDORA-2026-e1cac11588 has been pushed to the Fedora 43 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-e1cac11588`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-e1cac11588

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 6 Fedora Update System 2026-09-29 02:11:27 UTC

FEDORA-2026-93f562a43f has been pushed to the Fedora 44 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-93f562a43f`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-93f562a43f

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 7 Fedora Update System 2026-10-01 01:12:41 UTC

FEDORA-2026-93f562a43f (xdg-dbus-proxy-0.1.9-1.fc44) has been pushed to the Fedora 44 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 8 Fedora Update System 2026-10-03 00:24:51 UTC

FEDORA-2026-f10257ca80 (xdg-dbus-proxy-0.1.9-1.fc45) has been pushed to the Fedora 45 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 9 Fedora Update System 2026-10-14 01:29:50 UTC

FEDORA-2026-e1cac11588 (xdg-dbus-proxy-0.1.9-1.fc43) has been pushed to the Fedora 43 stable repository.
If problem still persists, please make note of it in this bug report.