CVE-2025-66469
NiceGUI Reflected XSS in ui.add_css, ui.add_scss, and ui.add_sass via Style Injection
MEDIUM 6.1EPSS 0.3%
NiceGUI is a Python-based UI framework. Versions 3.3.1 and below are vulnerable to Reflected XSS through its ui.add_css, ui.add_scss, and ui.add_sass functions. The functions lack proper sanitization or encoding for the JavaScript context they generate. An attacker can break out of the intended <style> or <script> tags by injecting closing tags (e.g., </style> or </script>), allowing for the execution of arbitrary JavaScript. This issue is fixed in version 3.4.0.
- Affected
- zauberzeug · nicegui
- CVSS v3.1 GITHUB
- 6.1 MEDIUM
CVSS: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, 19th percentile
- Published
- 2025-12-08
- Updated
- 2025-12-09
Proof-of-concept exploits (1)
Security advisories
- zauberzeug/nicegui/security/advisories/GHSA-72qc-wxch-74mg
- zauberzeug/nicegui/commit/a8fd25b7d5e23afb1952d0f60a1940e18b5f1ca8