CVE-2026-21872

NiceGUI apps are vulnerable to XSS which uses `ui.sub_pages` and render arbitrary user-provided links

NiceGUI is a Python-based UI framework. From versions 2.22.0 to 3.4.1, an unsafe implementation in the click event listener used by ui.sub_pages, combined with attacker-controlled link rendering on the page, causes XSS when the user actively clicks on the link. This issue has been patched in version 3.5.0.

Affected

zauberzeug · nicegui

CVSS v3.1 GITHUB

6.1 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS

0.27% chance of exploitation in the next 30 days, 18th percentile

Published

2026-01-08

Proof-of-concept exploits (1)

• advisories/GHSA-m7j5-rq9j-6jj9

Security advisories

• zauberzeug/nicegui/security/advisories/GHSA-m7j5-rq9j-6jj9
• zauberzeug/nicegui/releases/tag/v3.5.0

References

• CVE Record
• NVD entry