CVE-2026-21873: Zauberzeug Nicegui

Medium severity, CVSS 6.1. EPSS: 0.3% chance of exploitation in the next 30 days.

NiceGUI is a Python-based UI framework. From versions 2.22.0 to 3.4.1, an unsafe implementation in the pushstate event listener used by ui.sub_pages allows an attacker to manipulate the fragment identifier of the URL, which they can do despite being cross-site, using an iframe. This issue has been patched in version 3.5.0.

Affected products

• Zauberzeug Nicegui: from 2.22.0, before 3.5.0 (fixed in 3.5.0)

Published 2026-01-08. Last modified 2026-06-17.