CVE-2026-40354
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedFlatpak xdg-desktop-portal before 1.20.4 and 1.21.x before 1.21.1 allows any Flatpak app to trash any file in the host context via a symlink attack on g_file_trash.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceFlatpak xdg-desktop-portal before versions 1.20.4 and 1.21.1 contains a symlink attack vulnerability in g_file_trash that allows any sandboxed Flatpak application to trash files outside its sandbox in the host context, enabling unauthorized file system access.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 1.20.4= 1.21.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- High
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check if xdg-desktop-portal is installedRun 'which xdg-desktop-portal' or check your package manager (dpkg -l | grep xdg-desktop-portal, rpm -qa | grep xdg-desktop-portal)Affected if xdg-desktop-portal is not found on the system - the vulnerability does not apply
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Determine the installed version of xdg-desktop-portalRun 'xdg-desktop-portal --version' or check via package manager: 'dpkg -s xdg-desktop-portal' (Debian) or 'rpm -qi xdg-desktop-portal' (RHEL/Fedora)Affected if Command fails or package not found - portal is not installed
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Compare installed version against affected rangesThe affected versions are: < 1.20.4 and = 1.21.0. Compare your installed version from step 2 to these rangesAffected if Installed version is less than 1.20.4 OR equals exactly 1.21.0 - the system is vulnerable
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Verify xdg-desktop-portal is actively running (required for exploit)Run 'ps aux | grep xdg-desktop-portal' or check for the portal socket at ~/.cache/xdg-desktop-portal or /run/user/<uid>/xdg-desktop-portalAffected if Portal is not running - the specific attack vector may not be reachable even with a vulnerable version
You are affected if xdg-desktop-portal is installed, running, and its version is either below 1.20.4 or exactly 1.21.0.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped1.20.4
Update xdg-desktop-portal to version 1.20.4, 1.21.1, or later to patch the symlink attack vector in g_file_trash.
xdg-desktop-portal >= 1.20.4 or >= 1.21.1
- Update your system package manager to get the latest xdg-desktop-portal packages
- For systems using package managers (apt, dnf, pacman, etc.), run: sudo apt update && sudo apt upgrade xdg-desktop-portal (or equivalent for your distro)
- After updating, restart the xdg-desktop-portal service if it is running: systemctl restart xdg-desktop-portal or kill the running process to force restart on next use
- Verify the installed version matches or exceeds the fixed release: xdg-desktop-portal --version
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-40354 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-40354 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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