CVE-2026-40354

Host-file trashing via TOCTOU symlink redirection

Published Apr 11, 2026 · Updated Apr 11, 2026

Symlink following in Flatpak XDG Desktop Portal before 1.20.4 and 1.21.0 allows local users to trash arbitrary host files. The portal passes a path traversing a client-controlled directory tree to g_file_trash, permitting a TOCTOU symlink redirection outside the sandbox. Any Flatpak app can trigger the race, and the bounded consequence is moving a host file to trash rather than reading its contents or executing code.

CVSS severity2.9
Low
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Symlink following in Flatpak XDG Desktop Portal before 1.20.4 and 1.21.0 allows local users to trash arbitrary host files. The portal passes a path traversing a client-controlled directory tree to g_file_trash, permitting a TOCTOU symlink redirection outside the sandbox. Any Flatpak app can trigger the race, and the bounded consequence is moving a host file to trash rather than reading its contents or executing code.

The record

CVE
CVE-2026-40354
Published
Apr 11, 2026
Updated
Apr 11, 2026
Vendor
Flatpak
Product
XDG Desktop Portal
Classifications
CWE-61, T1485
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.20.4
  2. Affected versionversion=1.21.0 <1.21.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Flatpak · XDG Desktop Portalversion=0 <1.20.4; version=1.21.0 <1.21.1

Published CVSS scores

2.9MITRECVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
6.3NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H
5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-61UNIX Symbolic Link (Symlink) Following
T1485Data Destruction

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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