CVE-2026-21872

EUVD-2026-1477 · Published Jan 8, 2026

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.

Technologies

Zauberzeug NiceguiNicegui Nicegui

Weaknesses

CWE-79

CVSS scores

v3.16.1CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

MITRE ATT&CK

Inferred

Where this vulnerability fits in an attack

ReconImpact

Initial Access

T1190Exploit Public-Facing Application

References

https://github.com/zauberzeug/nicegui/security/advisories/GHSA-m7j5-rq9j-6jj9
https://github.com/zauberzeug/nicegui/releases/tag/v3.5.0
https://nvd.nist.gov/vuln/detail/CVE-2026-21872
https://github.com/zauberzeug/nicegui

Potentially impacted assets

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