CVE-2026-21873
High · 7.2NiceGUI apps which use `ui.sub_pages` vulnerable to zero-click XSS
CVSS
7.2
EPSS
0.3%
Published
Jan 8, 2026
CISA due date
—
The record
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_.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| PyPI | nicegui | 2.22.0 | 3.5.0 |
| pypi | nicegui | 2.22.0 | No fix |
Related vulnerabilities
- GHSA-mhpg-c27v-6mxr NiceGUI apps which use `ui.sub_pages` vulnerable to zero-click XSS Same vulnerability
- GHSA-78qv-3mpx-9cqq NiceGUI vulnerable to XSS via Code Injection during client-side element function execution Also affects nicegui
- CVE-2026-27156 NiceGUI is a Python-based UI framework. Also affects nicegui
- CVE-2026-25732 NiceGUI is a Python-based UI framework. Also affects nicegui
- CVE-2026-25516 NiceGUI is a Python-based UI framework. Also affects nicegui
- GHSA-9ffm-fxg3-xrhh NiceGUI's Path Traversal via Unsanitized FileUpload.name Enables Arbitrary File Write Also affects nicegui
- GHSA-v82v-c5x8-w282 NiceGUI's XSS vulnerability in ui.markdown() allows arbitrary JavaScript execution… Also affects nicegui
- GHSA-mp55-g7pj-rvm2 NiceGUI has Redis connection leak via tab storage causes service degradation Also affects nicegui