TI-2025-40896 Aliases CVE-2025-66469 GHSA-72qc-wxch-74mg

NiceGUI Reflected XSS in ui.add_css, ui.add_scss, and ui.add_sass via Style Injection

MEDIUM 60CWE-79Published 2025-12-08 · Updated 2025-12-09

Key facts

Attack vector: Network
Privileges required: None
User interaction: Required
Attack complexity: Low
Impact type: Cross-site scripting
Confidentiality · integrity · availability: Low · Low · None
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-79.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00275 20th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Fixed nicegui (zauberzeug): 3.4.0nicegui (PyPI): 3.4.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
zauberzeug	nicegui	before 3.4.0	3.4.0	Patch available	CNA
—	nicegui (PyPI)	before 3.4.0	3.4.0	Patch available	GHSA-72qc-wxch-74mg

nicegui Vendorzauberzeug Affected before 3.4.0 Fixed in 3.4.0 Patch available CNA
nicegui (PyPI) Vendor— Affected before 3.4.0 Fixed in 3.4.0 Patch available GHSA-72qc-wxch-74mg

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:zauberzeug:nicegui::::::::	before 3.4.0	Vulnerable	zauberzeug

cpe:2.3:a:zauberzeug:nicegui:*:*:*:*:*:*:*:* Versions before 3.4.0 Vulnerable ·zauberzeug

Remediation

Fix · CNA nicegui (zauberzeug) Fixed in 3.4.0
Fix · GHSA-72qc-wxch-74mg nicegui (PyPI) Fixed in 3.4.0 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2025-66469
2026-10-03 Alias added: GHSA-72qc-wxch-74mg

References

TI-2025-41029 NiceGUI Path Traversal Vulnerability in app.add_media_files() Allows Arbitrary File Reading CVSS 3.1HIGH 7.5
TI-2026-17574 Zero-click XSS in all NiceGUI apps which uses `ui.sub_pages` CVSS 3.1HIGH 7.2
TI-2026-17575 NiceGUI has Redis connection leak via tab storage causes service degradation CVSS 3.1MEDIUM 5.3
TI-2026-17573 NiceGUI apps are vulnerable to XSS which uses `ui.sub_pages` and render arbitrary user-provided links CVSS 3.1MEDIUM 6.1
TI-2026-17572 NiceGUI is vulnerable to XSS via Unescaped URL in ui.navigate.history.push() / replace() CVSS 3.1MEDIUM 6.1
TI-2025-40897 NiceGUI Stored/Reflected XSS in ui.interactive_image via unsanitized SVG content CVSS 3.1MEDIUM 6.1

See all 11 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences