XDG Desktop Portal: Path traversal in FileChooser.SaveFiles
Summary
XDG Desktop Portal before 1.22.1 does not validate the optional filenames passed to FileChooser.SaveFiles. A malicious sandboxed application can use this to create files that do not yet exist on the host, outside its sandbox, limited to locations the logged-in user can access. Exploitation requires a malicious or compromised sandboxed (typically Flatpak) application to be installed on the host.
Affected
- xdg-desktop-portal versions before 1.22.1 (up to and including 1.22.0)
Fixed in
- Upstream xdg-desktop-portal 1.22.1
- Debian testing and unstable: 1.22.1+ds-1
- Fedora 44: 1.22.1-1.fc44
- Alpine edge: 1.22.1-r0
- Gentoo: latest tree version listed as 1.20.4-r1, so still affected at the time of research
Workaround
- No vendor workaround known; apply the update.
- Remove unneeded Flatpak applications, especially those from untrusted sources, on Linux systems.
Exploitation
- Not known to be exploited in the wild. CISA SSVC: exploitation none, automatable yes, technical impact partial.
- No public proof of concept found at time of research.
Our recommendation
- Identify Linux workstations that run xdg-desktop-portal and Flatpak applications.
- Install distribution updates that include xdg-desktop-portal 1.22.1 or a vendor backport; prioritise systems still on 1.20.x.
- Review and restrict Flatpak installations on managed devices.
- Monitor vendor advisories for further updates.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-cm83-2936-gxjm github.com
- xdg-desktop-portal 1.22.1 release github.com
- VulDB entry 425783 vuldb.com
- Strix CVE mirror CVE-2026-55888 www.strix.ai
- NVD record via Vulners vulners.com
- Debian package tracker xdg-desktop-portal tracker.debian.org
- Fedora package xdg-desktop-portal packages.fedoraproject.org
- Gentoo package xdg-desktop-portal packages.gentoo.org
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 10:46.
Original description (NVD)
XDG Desktop Portal is a desktop integration portal. Prior to version 1.22.1, malicious sandboxed applications can use the FileChooser.SaveFiles method to gain arbitrary file access to non-existing files on the host (limited to files the user has access to). The FileChooser.SaveFiles method takes optional filenames which get appended to the selected directory by backends. The backends are supposed to check that the file does not exist yet. The filenames are not validated by the frontend and also not by common backends. This issue has been patched in version 1.22.1.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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