Predictable tokens in XDG Desktop Portal enable clipboard data theft
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- High · Low · None
- Fix status
- Partial Red Hat: 4 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat.
Summary
xdg-desktop-portal from flatpak before 1.22.1 generates tokens with GLib's pseudo-random number generator, which produces reproducible output (CWE-330). A malicious sandboxed application can recover the generator state by creating enough tokens, predict later tokens, and then use the FileTransfer.RetrieveFiles method to redirect drag-and-drop and copy-paste data meant for other applications to itself.
Written with Claude Haiku 5.5 from the sources below · 2026-10-28
Description from the CNA
XDG Desktop Portal is a desktop integration portal. Prior to version 1.22.1, malicious sandboxed applications can use the FileTransfer.RetrieveFiles method to redirect drag-and-drop and copy-paste data targeted at other applications to itself. Some portals generate tokens which provide access to resources. The sharing of the token transfers access to the resource and is supposed to happen out of band. The tokens were generated with g_random_int or g_uuid_string_random, both of which use GLib's GRand based on the Mersenne Twister PRNG which created a stream of reproducible random numbers. By generating enough tokens, the state of the GRand can be recover and with it, the next tokens can be predictedinsufin. This issue has been patched in version 1.22.1.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
Update xdg-desktop-portal to version 1.22.1, which contains the fix. Red Hat rates this issue Moderate and lists Red Hat Enterprise Linux 7, 8, 9 and 10 as affected with no plan available.
Written with Claude Haiku 5.5 from the sources below · 2026-10-28
- Fix · CNA xdg-desktop-portal (flatpak) Fixed in 1.22.1
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-23 Threatist record created from CVE-2026-55889
- 2026-10-23 CISA SSVC decision points changed
- 2026-10-23 Priority changed: MEDIUM → LOW
- 2026-10-24 Affected versions changed · Red Hat
- 2026-10-24 CVSS score added · Red Hat
References
More flatpak vulnerabilities
- TI-2026-28833 flatpak-builder has a path traversal leading to arbitrary file read on host when installing licence files CVSS 4.0HIGH 7.1
- TI-2026-26401 Flatpak has a complete sandbox escape leading to host file access and code execution in the host context CVSS 4.0CRITICAL 9.3
- TI-2024-28440 Flatpak may allow access to files outside sandbox for certain apps CVSS 3.1CRITICAL 10.0
- TI-2023-12679 TIOCLINUX can send commands outside sandbox if running on a virtual console CVSS 3.1CRITICAL 10.0
- TI-2026-79756 Path traversal in XDG Desktop Portal allows arbitrary file access CVSS 4.0HIGH 8.8
- TI-2026-26402 Flatpak affected by arbitrary file deletion on the host filesystem CVSS 4.0HIGH 8.7
Sources
- CVE-2026-55889 · CVE Program
- CVE-2026-55889 · NVD
- FIRST EPSS
- CVE-2026-55889 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences