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.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-72qc-wxch-74mg NiceGUI Reflected XSS in ui.add_css, ui.add_scss, and ui.add_sass via Style Injection
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 11 Dec 2025 16:15:00 +0000

Type Values Removed Values Added
First Time appeared Zauberzeug
Zauberzeug nicegui
CPEs cpe:2.3:a:zauberzeug:nicegui:*:*:*:*:*:*:*:*
Vendors & Products Zauberzeug
Zauberzeug nicegui

Tue, 09 Dec 2025 17:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 09 Dec 2025 10:15:00 +0000

Type Values Removed Values Added
First Time appeared Nicegui
Nicegui nicegui
Vendors & Products Nicegui
Nicegui nicegui

Tue, 09 Dec 2025 00:00:00 +0000

Type Values Removed Values Added
Description 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.
Title NiceGUI Reflected XSS in ui.add_css, ui.add_scss, and ui.add_sass via Style Injection
Weaknesses CWE-79
References
Metrics cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2025-12-09T16:03:54.125Z

Reserved: 2025-12-02T15:43:16.586Z

Link: CVE-2025-66469

cve-icon Vulnrichment

Updated: 2025-12-09T14:18:07.181Z

cve-icon NVD

Status : Analyzed

Published: 2025-12-09T00:15:49.330

Modified: 2025-12-11T16:00:55.153

Link: CVE-2025-66469

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2025-12-09T10:04:45Z

Weaknesses